I recently had a problem with the wire feed on my sealey 130XT, whereby the wire feed feed motor would run at full speed no matter what the control knob was set at. After doing a bit of research the problem seemed to point towards the SCR/ thyristor TL6006, I managed to find a thyristor of a similar value from an old washing machine PCB & fitted it to test it. This appeared to solve the problem. So i tried to find another TL6006 thyristor, i soon found out that this thyristor is now obsolete & difficult to get hold of, so i decided to slightly uprate to a S6010L thyristor which can also be heat sink mounted. . I fitted this thyristor & tested the welder,but i also noticed that the white resistor got very hot,& realised that the heat may also affect other components mounted near to it, so i decided to replace this with one of the same resistance, but 25w instead of the original 7w,& the new one also has aluminium cladding & can be mounted remotely on a heat sink. So i found a piece of aluminium & mounted the thyristor & the resistor on the aluminium plate. I am certainly no expert when it comes to electronics, but logic would suggest that these things should work better when the operating temprature is kept as stable as possible. First indications appear to show that the wire feed is now more stable especially when the welder has been used for a considerable amount of time, & does not need constant readjustment,..as it did before the fault !