Check your bearings closely for wear and damage. Surface grinders live in a world of metal grit and grinding wheel dust, which must be kept out of the bearings, or they will rapidly get damaged. Make sure you have some kind of sealing system that works properly, no missing parts or aftermarket wannabe sealing, everything in the bearing area tight and spotless when it goes back together.
The bearings are smooth.
I was thinking about flushing out the bearings with kerosene and soaking up the remainder.
I guess I'll never know what oil to run ....