Help repairing an Original 75 needed.

[wonky donky]

Obviously without seeing the parts I can't say for certain but I suspect the cause of the chipped teeth is because one piston has a greater stroke than the other, this need only be 1mm or less to create a problem. The same thing can happen when a rifle is fired with seals that have reverted & broken up.

If you look at the rear cap beneath the top washer you may notice the washer beneath has a size stamped on it, this is to remove excess or reduce stroke so there's no undue pressure on the parts when assembled.

The parts are 15 & 16 on the factory drawing, unsurprisingly Chambers show them but don't list them.

Part 15 the one benaeth is a steel spacer for the To1 comes in 0.2 0.4 0.6 0.8 1.0 1.2 & 1.4

Part 16 is just the 0.5mm washer that sits on top.

[Mr.Fixit-Norm]

Obviously without seeing the parts I can't say for certain but I suspect the cause of the chipped teeth is because one piston has a greater stroke than the other, this need only be 1mm or less to create a problem. The same thing can happen when a rifle is fired with seals that have reverted & broken up.

If you look at the rear cap beneath the top washer you may notice the washer beneath has a size stamped on it, this is to remove excess or reduce stroke so there's no undue pressure on the parts when assembled.

The parts are 15 & 16 on the factory drawing, unsurprisingly Chambers show them but don't list them.

Part 15 the one benaeth is a steel spacer for the To1 comes in 0.2 0.4 0.6 0.8 1.0 1.2 & 1.4

Part 16 is just the 0.5mm washer that sits on top.

Hmmm looks like I might have an issue here, I only have one washer in my assembly and it has what looks like a small cross head screw in the middle, where it goes through the washer it's formed into a dome which matches a domed recess in the end cap.

The info on Gavin's site shows as you say two washers, and info that says when assembled, there should be 0.3mm gap between the end washer and the piston washer. I think I'll have to wait till the Pistons are assembled so I can measure the gap before I decide what to do.

I'm guessing that the spacers aren't available any more either

I'll try and get some pictures up on my site later, might help with any ideas !

Norm

[Mr.Fixit-Norm]

Hi Norm, a few years ago there was a step by step guide in one of the Airgun mags of a strip and re-build of the giss system that ran over two issues, I had a 66 at the time and kept the guide in case I needed it (I didn't ) sold the rifle but the but still have the guide, if it is any help to you I will dig it out and post it to you,send a pm with your address and I get looking for it. Regards John

Hi, John,

Stripping guide arrived safely yesterday, it does look as if the trigger is essentially the same, should prove very useful.

Once again, many thanks.

Norm

[pegasus]

Hi, John,

Stripping guide arrived safely yesterday, it does look as if the trigger is essentially the same, should prove very useful.

Once again, many thanks.

Norm

No problem Norm, happy to help.