[jayco]

So you haven't moved the welder or the table in the past 6 months?
Nothing has been changed in the power supply to the welder?
Are you getting adequate voltage to the welder?

We once had a situation in which we thought every appliance in the house and my arc welder were on the 'blink'.......turned out the power company's transformer on the pole was going bad.

If the welder performs properly when the table is not involved with the circuit, one would think the table would be the problem.

"Resistance" could be part of the problem

If the 'route to ground' on the table is excessively long........and the table has sufficient mass, there could be problems.

Resistance is the main reason your not supposed to use a 500 ft. extension cord.

I would try the jumper and see if it helped........I don't think it could hurt anything, and might help diagnose the problem.