A chap posted this up on the other forum
"I striped my granddaughters diana 36, gave it a good internal clean and Polish, fitted a new spring and purchased a new leather piston seal, I left it to soak in neatsfoot oil for 24 hours, I proceeded to fit all the new bits and got the gun back together firing off a dozen shots it was smooth and hit the target, then power dropped off so I changed breach seal to no effect so striped the gun thinking a broken spring but on inspection I found the piston seal had crumbled like powder I'm not sure but it looked like a synthetic material? so beware if buying this so called leather seal, I am in process of now making my own , £18.50 for a rubbish seal I don't think so. Rant over."
He also said
"I don't want to name names, but it was located in Warwickshire." so we have a fair idea where it came from.
I have heard of other leather seals not being very leather like but not sure where they were purchased from.
Also, someone else has mentioned that the Webley pistol main springs that Protek sell are not very good. The W25p ones
I've not tried either product but if the parties concerned read this, (or maybe anyone else) would they like to comment?