Belt thickness. The speed relates to the middle of the belt. So speed off, get a thinner or thicker belt. Thicker would speed it up, thinner slow it down.
Do NOT forget: measure the speed with an LP playing!! the Lp playing on many belt driven TTs WILL slow it down a bit. So if you check it only with no Lp playing, it may run slow when it IS playing a LP.
This does not happen (usually) on direct drive TTs.
Do NOT forget: measure the speed with an LP playing!! the Lp playing on many belt driven TTs WILL slow it down a bit. So if you check it only with no Lp playing, it may run slow when it IS playing a LP.
This does not happen (usually) on direct drive TTs.

