Well, I've got a pair of used belts for my tape deck (thanks spoofington!), but I figure if I'm going this far, I might as well buy a new set instead of chancing 30 year old rubber inside my boombox.

So, where does one go to order new belts? And how do I measure them properly?

Dont know what your tape deck is; boombox? brand? model number?

Is this for a 'tape deck' = Home deck or boombox?

Have you tried Google?  ( tape deck or boombox??  = Brand, Model number, + "Cassette drive belt" ) Searching for?

First picture in this thread (below) should give you a idea about how to measure for belts, then you simply double that measurement.

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