HI if you look back at previus posts it will explane how its done.Havent noticed that the clutch is any heavyer or anything, It seems to bite in a slightly different place thats all. Fingers crossed it seems ok up to now.
Cannot tell you what size, it was about 15mm dia but wouldent swear to this. I had afew in my box so just kept trying till I found one that fit. Try halfords or your local ironmongery shop and get a selection . When you sort it measure size of ballbearing so others will know in future.I should of done this sorry i cannot be off any more help.
the pipe under my car measured 8mm and plumbcentre do a compression endcap for about £1 that way capping the pipe off and if its good enough to hold gas off it should be good for clutch fluid I reckon
take out pipe and there will be a flare in end of pipe, bearing needs to sit in flare should be able to get ball from old bearing etc, put ball in block and refit pipe and tighten, job done.