Inside the piston is a steel top hat. It serves as kind of a front spring guide and it MUST be removed or you will be unable to cock the gun. If you use any kind of degreaser in there try really hard not to expose your piston seal or other non metal parts to it. Generally you can spray a bit of carburetor or brake cleaner in there and swish it around with a Q tip to cut the grease. You may then be able to tap the latch rod on a table top and have the top had drop out.
Rather than a solvent like brake or carb cleaner, what about something like kerosene? Would that still be an issue if it came into contact with the piston seal?
Another washer piston question, I did get the VortekPG3 HO kit installed in my TX 200. There were no washers in the bottom of the piston. It was a very simple process; take out stock spring , top hat and guide , then put in Vortek spring guide and top hat and Boom! done! Does it ever work well, unbelievably accurate and smooth. I am now attempting to install a pG3 low power 12ft lb Vortek kit in my HW97k and have run into the same problem. Unlike my tx 200 , once the stock spring was removed, there does appear to be a couple of washers on the bottom of the piston. But they will not budge? I soaked the bottom of the piston in brake fluid then tried to tap them out quite roughly but no go? Has anyone dismantled the HW97 piston ( maybe 77 also) and is there actual washers in there? Maybe the ones I seem to see are actually a permanent piece of the piston? Darn! Maybe I have to rip of the piston seal to get at them. I have never replaced a seal so not sure what's under there.Any help with this would be greatly appreciated, Thanks, Al