Success!!
Thanks to Michael kindly providing an actual red arrow pointing to the target spot I was able to replace the fuse and (perhaps miraculously) the machine now powers up. I've attached a couple of images. My soldering won't be winning any awards but now the machine is (mainly) working again.
Wrestling ther transformer back into position was a pain but other than that it was pretty straightforward.
So the original problem remains. The tape is not playing at the correct speed. I can get the right hand take up motor turning okay (albeit with a flick of the hand) but then the music emitted by the built-in speakers is way too fast. Sometimes it slows right down and stops. I know you mentioned to replace the drive belts and I've now ordered some and also plan to lubricate as suggested and I've found an old manual telling me how to do this. Any recommendations for a suitable oil? The research I've done on this throws up contradictory suggestions?
I'm pretty confident now I can get this beautiful machine functioning properly and I'm very grateful for the help received
Thanks so much!