Thanks for the welcome Martin, and for the advice.
I just acquired a used "replacement" deck on eBay, but it's had a hard life and needed a little tlc to get it to work. Adjusting the "forks" that keep the casette in place seems to have got it sorted.
I'd really like to get my own one back in working order as it's in known good condition with all the original screws, plus a extra washer that appeared from somewhere!
Richard