Replace main seals in Diana/Original/Gecado Model 10

Remove the locking screw from the spring cap.


Using a woodwork vice, and a water pump wrench with some protective alluminium or lead sheeting, undo the spring cap 1 turn only.


Using a suitable sash cramp, unscrew the spring cap whilst also undoing the sash cramp until the spring cap comes loose.

If you don't have a sash cramp, unscrew the cap carefully and be prepared to take the sudden release of the spring. In the original German spec (approx 3 ft lbs) the spring will not be dramatically strong, but having the gun in a cloth bag whilst unscrewing may give more confidence that things will not fly about.


This is as far as the spring will eject the cap.

Remove the dummy piston and springs/guide-rod assembly from the gun.


Using a wooden probe on the pinion gear teeth start to extract the main piston. Towards the end you will be able to pull it through with an index finger.

You will have to jiggle the sear lever at times to get the piston past it. The sear lever is pushed forwards from the back of the handle with the middle finger as shown in the pic.