Thank you for the comments. Yes, I think I will get the MZ-R50 fixed (I used to fix the MZ-R1 model in my Mastercare days but sadly I don't work there any more). Any UK based repairers that come recommended? I have been mainly using my MZ-R30 over the years and that is a solid machine too - anyone here own that model?
My 510 has not given a problem as of yet - what is it that goes wrong with them? I will have the 980 I think because it is not often that I see any decks for sale from someone I know. Does the 980 have the mono problem? I never knew of that issue, but I mainly use mono to record a music programme and then edit out the talking and still be able to fill an 80 minute CD.
It does seem from my limited reading so far that modern MD users work in conjunction with a computer, however it was the fact that I could do editing, copying and recording without a computer that made MD special, however Sony must move with the times and use in conjunction with a computer is probably helpful at times.
Anyway, I have a lot of learning to do as I have just been in my own MZ-R30 and 510 world for 13 years now.
Thank you again.