How to fit a V-Mach tuning kit on a Weihrauch HW97K rifle [Step by step tutorial] Solves dieseling 

You can skip the intro jumping to 3:35. Tutorial begins with the rifle completely disassembled. The fitted kit is rated at 16 joules.
Contents (serves as a step-by-step guide):
- 2:54 : Briefing on how to dissassemble the rifle
- 3:35 : List of materials needed for the tune up
- 4:40 : Instaling the new piston seal
- 5:05 : Fitting the piston sleeve
- 5:53 : Greasing the piston, the seal and cylinder
- 6:51 : Inserting the piston into the compression chamber
- 7:05 : Inserting the assembled cylinder into the action
- 7:22 : Assembling the cocking lever and the anti-bear trap
- 8:13 : Inserting two compression washers into the cylinder
- 8:38 : Applying grease behind the compression chamber
- 8:44 : Greasing the main spring
- 8:57 : Inserting the spring into the action
- 9:06 : Screwing back the rear block
- 10:11 : Screwing back the large bolt retaining the anti-bear trap
- 10:43 : Inserting the safety mechanism
- 10:52 : Mounting the trigger assembly (Actually, trigger unit disassembly is optional and the rear block may be easily screwed and tightened by hand. I have disassembled it for inspection, avoid damaging it and access the trigger mount hole for better leverage during the rear block screwing process)
- 11:38 : Mounting the stock to the rifle
- 13:52 : Fitting the scope
- 14:54 : All done - overview of the surplus bits (compression washers, nylon washer, oil, grease and the old spring and seal)
- 15:01 : Final comment
Considerations:
- Bear in mind that older rifles with a serial number below 1446649 use a 25mm piston seal. Newer units mount a 26mm one.
- Check your country air rifle power limits prior to buying a tuning kit and chronograph the rifle after the tune up to make sure it falls within your country regulations.
- When disassembling the rifle make sure you don't lose the safety catch spring. It has a natural tendency to fly away.
- The coking lever & trigger unit pins should come loose without too much effort. If you are struggling, try using the punch from the other side. (Same applies when mounting them back).
- Do not apply grease on the piston seal face. Only coat the sides very sparingly or dieseling may occur.
- The trigger mechanism can be a pain to install. Use two pin punches to align the holes.
- The oil supplied in the V-Mach kit is only for the exterior of the rifle. Do not use it in the piston, cylinder, seal or spring.
- Some people lightly sand the piston and cylinder after degreasing. I haven't done it and the V-Mach fitting instructions omits this step as well.
- The trigger unit may be left assembled during this procedure if the rear block is easily screwable an tightenable by hand.
Thank you for watching, hope you found it useful and happy field targeting. Any question/comment please feel free :-)
Disclaimer: The information provided here is for informational purposes only. Follow the instructions at your own risk