Timing belt issues

[ColoradoSteve]

I just adjusted the timing belt, it needed a bit of tightening, set it at about 38 and it seemed fine. After the motor ran for a while, the belt migrated back towards the engine and is now rubbing slightly against the rear cover. Does this mean it's too tight or too loose? Will readjusting it pull it back or do I have to loosen the belt and pull it forward then readjust?
Steve
'83 944

[Slam]

I'd check the idlers and tensioner. When the bearings start to go the belt will 'walk'. Also, your inner timing cover may not be seated properly. Problem might not be the belt at all.