The big grinder went down last night just as I was washing up to leave (after having already worked 11 hours that day). It was a bit of an electrical oddity and I thought I'd ask around to see if anyone knew of a likely root cause and preventative treatment.
The grinder is in poor shape, I know that, new knives and screen are going to be installed soon (when they arrive from the source) but right now it runs like crap and plastic is getting into the bearings which can make for a very high-load startup. The weirdness is that 100HP AC induction motor's starter, which is a relatively recent model and looks to be in excellent shape, has gotten a bit lazy. I find that if I shut off the disconnect and turn it back on then on the third or fouth push of the start button the contactor will close and all will be well, but only if I hold in the start button for a few second. If I push it quickly then the motor will start and quickly stop as if the auxilliaries are not closing. The buttons and contactors are all in good shape (except for one e-stop, but I put new contacts in the E-stop last night, so it should be okay).
Has anyone ever encountered this kind of behaviour before? I haven't pulled the starter apart yet, because I wanted to get home, and I'll be able to work on it Monday morning.

I heard of a similar problem in a plant before.

Frequent equipment start up and switchover can encourage this starter problem.

What is e-stop? Is it emergency stop?

Yes, an e-stop is an emergency stop palm-button of the type that once pressed it stays pressed until deliberately un-pressed.