Got the 10 fuses at 27.5p each and the first one seems to have survived. So I now have 9 fuses which may not be needed in the forseeable future, plus a(nother) currently working midi stereo which is about 18 years old.
Value of the stereo? £10 probably.
However it gives me a good feeling to not throw away something that is still viable.
What it did illustrate is how much the consumer electronics market place has changed since I was a lad. There used to be repair shops all over town with lots of spares and dedicated fettlers. Then again, stuff used to fail all the time. Now electronics are so reliable, so difficult to fix if they break, and so cheap to replace that there is no money to be made in repairing them. Can't see anyone making money repairing a stereo worth £10 once every 18 years. You have to go to t'Internet to get simple things like fuses.
Anyway, thanks for the help in identifying the correct fuse.
Cheers
Dave R