Thanks for all your responses, very appreciated.
I didn't see /handled the gun at all, and the WTS came up on a local forum. The deal seems "honest", as the seller immediately mentions the issue. The gun itself tempted me, nothing really visible on the picture - see attached - and I wanted to make sure the sticky chamber diagnosis was ok for an overpressure. The seller responded to my question, confirming it happened with anything between .38 SP Wadcutter and .357 Magnum.
The responses received here confirmed me the overpressure story was very plausible, so I decided to pass. Spare parts (especially a cylinder) is only possible by taking parts from another gun, and the swapping requires us in Belgium to have the gun re-tested by the official test bank (with cost and admin hassle).
With wheelguns going down in popularity, prices for these are coming down very low, so I would be able to find a similar gun in perfect condition for 3/400 $.
Anyway, I got the answer I needed - thanks again.
