I have an Teac X-2000r reel to Reel,machine was playing sluggishly,i changed the belt,it plays fine expect that now it only plays on one channel the left side,right side just has a hum,weather playing it thru the head phones or the amp,checked all wiring and it all seems to be in place,any clue on why? Before changing the belt had out puts on both channels.
Swap the RCA cables generally used for the output to an amp Left to Right.......The connectors on these can be a little fragile and the give-away variety that comes with much equipment are downright cheap. The hum will, of course, stay with the bad cable.
You might have bumped the connections on the back of the playback head, too.....when removing the various covers and such when getting TO that belt.