OK thanks for the advice everyone great stuff. Another question though-

 If i start to remove ball swirl a bit a time (i'm not going to rush this), can i still play the machine in between cleaning without waxing etc? I mean, do i have to complete the whole job, then wax before i use the machine? Will using the ME leave the playfield 'unprotected' if a play the thing without waxing? Stupid question maybe but i don't want to hurt anything! Thanks.

I usually remove all the hardware on a playfield (don't HAVE to do it), so I never play while cleaning. I would finish the process, then wax and play.