I’m constantly on the look out for a beogram 4000/4002/4004 on Scandinavian auction sites but no luck so far :). Seem as the prices on these sought-after models have almost quadrupled in the last 4 years.
For the wood frame/trim I would check this blog, he’s fitting a Beogram 4002 plinth to a 4000: https://beolover.blogspot.com/2020/06/beogram-4000-exchanging-plinth-panels.html
This danish shop sell a lot of parts for Beograms, including belts for 4002: https://www.beoparts-shop.com/product/belt-for-carriage-servo-motor-beogram-4000-4002-4004-6000-tangential/
