The weakest is 2KVA right up to a 6KVAHow powerful is/are the generator(s)? Maybe it/they can't provide the inrush current to start the grinder moving.
I have had the same problem in the past.My Makita "go to" grinder works perfect out the sockets but it just will not run from generators...
This i will try..cheersI have had the same problem in the past.
Plug an electric fire or other resistive load into the other generator socket so it is already supplying current when the grinder is switched on.
I thought this Pete, so wound it up on the sockets then changed it to genny while it was still running down and nothingI think it will be the soft start switch. If it's not soft start then I don't know.