The three machines that I have all had new balls / or good quality balls when I got them (with IM probably the exception) - and I don't know what is what.
I did give the IM a good clean yesterday and noticed the balls had alot of ultra fine powder on them - so cleaned under the apron, all over the playfield etc and the balls and then had 20 odd games with no dramas. There was no switch faults and everything seems fine on that side of things. I will place a order for balls today Greg so I can do a change out as I think these balls have had a good use out on the field anyway.
Thanks again for everyone's comments - I will just observe any issues until the balls arrive and then see if I can get a good amount of games on it without any dramas.