I have a dishwasher where the main pump doesn't always start. I've checked
and typically the impeller creeps round but doesn't always run up to speed.

Essentially the drag on the moving seal is too high.

I have tried Vaseline and the pump worked for a period of time reverting
back to its old tricks.

I then tried the opposite and cleaned the seal in detergent with initially
good results but again the drag went back to normal.

Any ideas? Is there a recommended lubricant? Would a new seal solve any
problem?