There is no real "manual" for my Weldmate 75, just a simple set-up sheet. Mine also came with a generic "Guide to Welding" that wasn't specific to the model. Here is the contact info for SIP. I have no idea if it is still current:
SIP (Holdings) Ltd
Gelders Hall Road
Shepshed
Loughborough
Leicestershire
LE12 9NH
Tel: +44 (0) 1509 500300
Fax: +44 (0) 1509 500456
Matt, May 2008