Hatsan Nova disassembly - seeking pesky air leak - pics added

[AmBraCol]

Hey guys, my Hatsan Nova is leaking badly.  Am trying to get to the internal o-rings to check them out but am having trouble getting the receiver disassembled.  Got the bottle off (THAT was on there tight!) and replaced the o-ring there, but that wasn't the problem.  So I've got the rifle apart, removed the barrel/shroud, removed the bottle, sitting here with the receiver in my hand and looking at the Exploded View PDF from Hatsan USA.  I removed the two screws that seem to secure the receiver from the hammer/bottle assembly (not sure of the proper terms - essentially the top assembly from the bottom assembly) and now it's loose - but wont come apart.  Hmmm.... looking at that PDF it's not really clear what's keeping it together.  Haven't been able to locate a disassembly guide on the 'net or youtube so am flying by the seat of my pants.  Here in Coffee Country I've not found anyone more qualified than myself to work on my airguns (that's not saying much, but it says a lot for the lack of knowledgeable techs) so sending it off is not an option.  If any of y'all have any experience trouble shooting the innards of a Hatsan Nova or AT-44 class rifle I'd appreciate any pointers you can point my way.  :-D

Attached are the right and left side views of where I'm at in the process right now.  Sure hope that left side sideplate doesn't have to come off - there's lots of fiddly stuff in there from the look of the exploded parts view. 

[Privateer]

Should only be 2 screws. One is under the bolt probe. Hold the cocking handle back and remove it.
Other is near the safety. Remove it after the one in the breech area.
Stuff will fall out like the safety and other parts so take it easy!
Now I have the trigger group remove where yours is still on place so maybe stuff won't fall out on you.

Though if the tank is leaking down? I highly doubt anything in that area is the cause.
I'd suspect the tank O-rings and such. Also maybe the pressure gauge and fill area or even the poppet itself.

[AmBraCol]

Should only be 2 screws. One is under the bolt probe. Hold the cocking handle back and remove it.
Other is near the safety. Remove it after the one in the breech area.
Stuff will fall out like the safety and other parts so take it easy!
Now I have the trigger group remove where yours is still on place so maybe stuff won't fall out on you.

Though if the tank is leaking down? I highly doubt anything in that area is the cause.
I'd suspect the tank O-rings and such. Also maybe the pressure gauge and fill area or even the poppet itself.

Thanks, Jeff.  Impatience won out.  There are three screws.  Will be uploading some pics in a bit...

[AmBraCol]

Here are some pics I took to document the disassembly.  Found the issue, nicked ring in the last pic.  Sure don't understand how it held air for over a year, and then leaked down and refused to air up again.  Weird.  AND it's a size that wasn't included in the rebuild kit so will have to wait until I can get into the store and try and find some.

[Privateer]

Yep. I see that 3rd screw now. I had just the AT44 breech sitting here that I'm converting to a .30
But I do see the seal is on the valve.

[AmBraCol]

Jeff, can you confirm that part number 2407 from the above referenced Exploded view is a thin wire spring?  As I was disassembling I found a thin wire spring and a steel bushing that I believe to be 2408 from the EV.  But they fell out (the bushing did, I had to pull out the spring) before I saw where they went.  The spring is trashed so will need to see if I can find something to replace it with...

[Privateer]

Part 2407 is missing in this hammer. May be why I got the gun for free since I was told it didn't shoot worth a darn.
 
Yes. 2408 is the steel bushing that goes between the 2 springs.

[Hobbyman2007]

The nicked o ring in the last pic has nothing to do with the ability to hold air . It is there only for when the trigger is pulled and the air makes its way to the transfer port . If the gun is leaking down , I guaranty it’s either the valve seat oring or the Guage . Best way to test is to air up as best you can and spray a water and liquid soap mix on any joints .

[AmBraCol]

The nicked o ring in the last pic has nothing to do with the ability to hold air . It is there only for when the trigger is pulled and the air makes its way to the transfer port . If the gun is leaking down , I guaranty it’s either the valve seat oring or the Guage . Best way to test is to air up as best you can and spray a water and liquid soap mix on any joints .

If it'd hold air, that'd be great.     It's going to get taken all the way down and every thing checked out and fixed as best as possible.  I've been putting it off too long, but it's on the "work table" now 'til it's done.  And it needs done as I've got another project for which that precious space needs to be freed up so the pressure's on to "get 'er done".  Thanks for pointing that out, I was looking at it backwards. Indeed there's no HPA in contact with that ring until the shot cycle releases it.

[Hobbyman2007]

Hang in there Paul. Finding leaks is not one of my favorite things to do but I’ve become somewhat good at it now mostly due to my tinkering habit. I just can’t leave well enough alone . While you’re in there you may as well check the alignment of the transferport and fill the extra holes that don’t line up , it will gain you a few shots at the least.

[AmBraCol]

Hang in there Paul. Finding leaks is not one of my favorite things to do but I’ve become somewhat good at it now mostly due to my tinkering habit. I just can’t leave well enough alone . While you’re in there you may as well check the alignment of the transferport and fill the extra holes that don’t line up , it will gain you a few shots at the least.

Thanks for the tip, Dennis.  I've been eyeing those excess holes with extreme prejudice and recalling some things rsterne wrote about them.  As this rifle will mostly be used around 12 FPE or so there's no need for excessive amounts of air to be blown behind the pellet.  Closing off the extras should help keep the air consumption down quite a bit. 

[Wayne52]

A bad fill probe o ring will leak down fast too, it seems to be the first thing to go on my pcp's, they take some abuse compared to the other o rings.