Can anyone help with advice on the following? I am having problems cutting threads successfully due to the tool seemingly cutting a different path on each pass. The result is a mess of multiple pitches, rather than a constant pitch thread. I have tried keeping the half nut engaged throughout and reversing the machine for each pass and also tried using the threading dial. Only tried cutting using the English Thread settings. The pictures attached of the magnified "thread" show an attempt at 12TPI on a piece of 3/4" brass rod. There seems to be an issue causing a lack of repeatibility in subsequent cutting passes. I can't find play on the slides, but wondered if the problem could be a missing tooth in the screwcutting gearbox, or play elsewhere (leadscrew) which could be the cause? Any pointers would be most welcome! Lathe is a Colchester Student 600, Mk2 square head.