My Bench grinder has a faulty 4uf capacitor so it wont spin up without help. I tried a 10uf of the same 400 ac 50/60 hz rating and it appears to work fine.
However, working fine for 5 -10 seconds test is encouraging but is there likely to be any problem using the larger capacity? It will fit easily into the base and its diameter is the same as the original, so the mounting clip is fine also.