Agree with everything above. I obtained a seal, spring and piston buffer kit with lube from Germany and following a YouTube vid, I had it stripped down in a couple of hours. I used needle pliers, a small punch, light hammer, screwdriver and a swiss army knife. As said by Paxil make sure the screwdriver is a good fit for the trigger group screws.

Stripdown and reassembly was absorbing and not at all difficult. There is a myriad of advice about lubrication however which is probably best left for the more knowledgable. I reassembled everything dry after a thorough clean and light polish of the piston. The only lube I used was a dab of moly grease on each end of the new spring and light oil to the external linkages. The old seal was prised out with a screwdriver (care needed to avoid damaging the seat) and I used a corkscrew to remove the piston buffer. Good for another 30 years!