Diana 240 trigger wont reset at times...

[Sneaky Fox]

I was wondering if anyone had any ideas on this. A while back I bought a Diana 240 that dieseled for a while, turned out to be a bad breech seal I didn’t initially notice. Then every couple shots when cocking, the spring would compress and be held compressed, but the trigger/safety itself would not reset and cock. By pulling down on the barrel a few more times I could usually get the trigger to reset (yes I was always pulling to the bottom of the stroke).

I took apart the gun suspecting maybe a loose piston stem that wasn’t fully engaging the trigger mechanism, and the stem was a little loose so I ordered a new piston, cleaned lubed and reassembled the gun, but the issue persisted.

Im thinking something might be off in the trigger assembly (?) but haven’t had the nerve to take apart the T05 unit and couldn’t find any good diagrams or videos. Does anyone have any idea why the spring might be held in compression but trigger not resetting? Alternatively, would one of the Chinese clone T05 assemblies work as a replacement to try out and see if it resolves the issue, and is there a source for them? A new T05 unit from what I’ve seen is around $100 which is about what I spent on the gun, so I haven’t felt it was worth it.

Any ideas would be appreciated! Thanks!

[Roadworthy]

Perhaps your trigger assembly is gummy / dirty inside.  Your trigger return spring may also be weak.  I believe the Chinese T05 from a clone should work.  Check with Mike Melick at Flying Dragon Air Rifles.  I doubt your problem is really severe, though.  Other members can probably advise you better than I can.  I've only been into T01 and T06 triggers.

[Sneaky Fox]

Thanks Roadworthy! I’ll take it apart again and try a thorough degreasing, hopefully it’s something simple along those lines. I was worried something may have been jarred out of place/broken by the dieseling, but don’t know much about the function of a T05 and couldn’t figure out why the spring would lock up compressed without the trigger resetting.

[joek]

IIRC plates #104 #105 can cause problems if assembled with the wrong face forward.

[Sneaky Fox]

Thanks for the tip and the diagram! When I get a chance to take everything apart I’ll check out those plates.

[travelbike]

Have the same gun and the same problem.  Disassembled trigger assembly and the wear I see is on part #52 as in the diagram. Seems like part#102 has eaten the lip on Part#52.  When you cock the gun,  a shaft on the piston with a semi ball end enters the trigger assembly and is locked by the plates labeled #104 and 105.  When you pull the trigger, I think it actuates Part 102 which pushes part #52.  The wear is at the point where 102 and 52 meets.  Attached is the picture of part 52 and a yellow highlight is where mine has worn out.

Let me know what you find out.  Mine is still disassembled.  You can buy Part 52 I think from UK air gun stores for about $15. Bought my gun cheap as well so not sure what to do.  Maybe use an electronic solenoid to just activate part 52 to allow it to fire and at the same time make it a bullpup.  Too many pending projects !

[Sneaky Fox]

Thanks that sounds like it could be what’s going on! If I find wear I’ll order a replacement part from chambers in the UK, hopefully get everything back together correctly, and hope it works.