RTC battery is mostly sorted, have found a close item from Farnell - physically a bit smaller, 65mAh rather than 90 but will fit PCB.
However an odd thing happened when I swapped it into the 9354T (the TM's battery is OK as it happens) - put new battery in and the 'scope wouldn't boot, fiddled around a bit including putting the old battery back but no joy. Left the 'scope on the bench overnight and mysteriously it booted fine the next day. I might have another go with a couple of flying leads to a backup even though the current battery is dead.
Encoders: It's the two "zoom" encoder shafts which are snapped, These are Bourns "ECW" series, one with detent "clicks" and one with a smooth non-detent action. Mouser stock the non-detent version but the detent version is a special order item with a MOQ of 300. Wound up with two of the detent version with 6mm shafts. ebay not much joy here in UK so might as well buy from Mouser as their shipping is reasonable.
Knobs - can't find anything which fits the .185" split shaft anywhere in the UK, or indeed anywhere; yes did try ebay. This is partly the reason I got the "wrong" shafts on the encoders. Found some OKW knobs from Conrad which aren't too far off. Slightly broader at the base (14.5mm vs 12mm approx) and a slightly different grey but I think they'll look OK.
Floppy: not sure I'll put a lot of energy into fixing the floppies. The 9345T drive works but doesn't pass the built-in test. Have tried new disks in case my 20 year old, alternately baked and frozen in the garage ones were shot but no joy. Also tried a different drive (still have a couple lying around) but much the same. Might swap the controller card from the 9354TM but that's about as far as I'll take it. The drive on the 9345TM is toast (sounds like the spindle lubrication has gone sticky).
I just need to find some time to get the old panel out and fit the new bits to it.