I just found out that a 0.050" driver is better for those screws even though it said 1.3mm on the suppliers' website.
http://cgi.ebay.co.uk/Hudy-Hex-Drive...item1c13efad61
The 1.3mm is OK but I've found it can strip the hex in the screw if tightened too much. Hope this helps.
Working on some new modifications e.g. plastic belt cover washers and underchassis weights. Don't touch that dial...