I had exactly the same problem re the cylinder/tap connection as you with a Webley Mark 3 about 18 months ago. I followed the instructions elsewhere on this forum for fixing a "porous breech" problem on an HW35, using Loctite 290. I applied it using a disposable syringe with a very long blunt needle, both bought online from a well-known retailer. The long needle made the stuff easy to apply. Left it a day or so to set. Touch wood, no problems so far.