REFURBISHING VINTAGE TUBE RADIOS-

I am looking at getting a vintage tube radio (German) but the seller has no way of testing it. Physically it looks like it's in 8/10 condition (or better!). where can i send it for a thorough repair and replacement service? I grew up with one of these-type units and it sounded really good with a decent 6x8 main speaker and a couple of side-firing tweeters. it was fun fooling around with the SW band too. Plus i really dig the wood finish on these older units. anyone with information please let me know. thanks!