Drive belt is an easy replacement (it’s a specific flat belt, but andmar and/or Jubilee have them). Table only traversing in one direction is either the Z travel stop being triggered and the seller not knowing, the link between the trip lever and the valve being broken/missing or a need to clean the control valve block, in that order. Not difficult in any of those, although the latter will involve the purchase/making of a gasket or two (gasket paper is sufficient).
The only thing better than a 540 would be a 1400. DAMHIKT 😀