Welcome to BoomBoxery, Geoff. You should be getting messages of some sort from other members before long.
Now, I suppose that the motors in your ‘3D80E are working, revving up when you try playing a cassette and so on – that they haven’t burnt out or aren’t somehow jammed?
And one must also ask: aren’t there any competent repairers of analog electronics such as 1980s boomboxes within, oh, fifty miles of where you live in the UK? (Could save you from being overwhelmed by a “do it yourself†attempt.)
And one also wonders: do the tape-deck rubber belts for your find by Hitachi have to sold by and shipped from a UK seller? There are several vendors of hobbyist rubber belt kits on eBay. Some of them would certainly be honest, competent sellers offering good products, even if they don’t live in Merrie England. But you’ve got scheduling concerns, I suppose. The sooner you receive the package of parts, the better, eh?
In that case, one can suggest the eBay seller cnh _ 03 (government name: Charles Holt, based in Lincolnshire; eBay member since April 2004). The seller apparently is apparently trusted by a large number of customers specifically seeking tape-deck rubber belts (or “hobbyist rubber belt kits,†at any rate). There seems to be no negative feedback rating of that member as a seller in the last year or so. A trustworthy fellow? One would hope so. The rubber bands this products of his has just might be what you need:
https://www.ebay.co.uk/itm/61mm-77mm-Flat-Rubber-Drive-Belt-for-Cassette-Decks-etc-PACK-OF-FIVE/193136754341?hash=item2cf7d8fea5:g:HGYAAOSwOZddlJmO
(A search term of “Cassette Deck belts†on eBay.co.uk will fetch reasonable results. Of course, one would still have to do due diligence, very carefully measuring the needed belts
if they haven’t “gone to goo†inside the stereo.)
The price of the one tape-deck rubber belt kit that the eBayer cnh _ 03 is selling seems cheap: £3.75 (about
US$4.85, according to a quick Google check). Of course, financial and emotional cost will rack up pretty quickly if one orders the wrong size or type of rubber belts (flat belts versus squared belts, etc.). So, again, one has to be careful. Oh, and the aerial (“antennaâ€) should be replaceable with a vintage Hitachi spare on eBay (if you happen upon one) or replaceable with a new, generic unit on Amazon.
Must dash now; running rather late for an important meeting. Take care.