start low and work upwards
UPDATE the wise man in maplins told me .
Just pulled the case off my 165E to look for you, my PCB has two fuses the top one is marked F10/250V as per previous post but the bottom fuse is marked F500ma/250V.
Moral of the story...stick your hand in your pocket & buy new!
Ive managed to keep my Pro90 going for 10 years, still works as well as it did when it was new, and for bodywork & chassis repairs it's adequate.