Replace main seals in Diana/Original/Gecado Model 10

Rub in a small amount of molybdenum disulphide paste onto the piston body and inside the pistol main spring chamber. This will form a dry-ish permanent lube.


Apply a sparing amount of gun grease on the springs - just enough to "wet" the springs and rod.




Carefully feed the piston back into the main chamber. The rack is on the grip side of the pistol so that the sear slots actuate against the sear. Putting it in 180 degrees out will not allow it to be cocked or fired!

There are several catch points in the cocking slot and trigger sear openings which will need the delicate washer lip to be carefully "shoe-horned" with a blunt screwdriver or hoof stick to prevent shaving off a piece of the nice new washer. These are sear, sear aperture front end, and then the front end of the cocking slot which needs the washer lip to be probed out of the way at two places simultaneously. You will also have to keep the sear out of the way at times.


Replace the cocking slide and the slide pin. It is easier to replace when the piston is not under spring pressure.


Refit the springs assembly, and attach the dummy piston onto the end of the springs, with cap attached. Locate in the sash cramp. Screw up the sash cramp, all the time ensuring the pistons are relatively in the correct opposing pisitions. Use a wooden stick to twist them into place through the pinion holes.

When the cap and the body are in loose contact, move the cap to the position you marked with the pencil and attempt to make the thread "bite" whilst applying light pressure with the cramp. If necessary push the pistol body rightwards with the left hand (the spring pressure is within human range of force!) Eventually the thread will bite and screw up the cap at least one turn.