Replacing the One-Stitch or Stop/Start Button Switch

Symptoms: Erratic behaviour of the machine consistent with a button being held in full-time. For instance: 1) at start-up the machine goes into adjustment mode then starts fast beeping as if you had held the switch in after actually starting it in adjustment mode (try it sometime with a normal button) would indicate a red 1-stitch button was failing. Or .. 2) machine suddenly starts to sew all by itself when maybe you’re nowhere near it – that’ll be it thinking the black stop/start button has been pushed.

PRO Handles:

The PRO has a very useful diagnostic to help identify the button that is sticking. See pages 25/26 of the manual. Either the Run light or the Fail light closest to the faulty switch will be blinking.

The buttons are held in the ends of the handles by tiny grubscrews on each side. Often, simply loosening these screws will fix the problem.

If not, loosen off the grubscrews entirely and extract the switch. Slice off any insulation covering the wires where they are soldered to the terminals. Unsolder the wires. Slip new heatshrink insulation over the wires and slide it down as far as you can without losing it in the handles – maybe tape it in place out of the way. Solder the new switch into place. Often good to have a spare pair of hands to help here. Try not to put heat on the switch terminals any longer than needed to make a good soldering joint. When the work cools a little slide the heatshrink up to cover it. A paintstripper gun is ideal to activate the shrinking process, but a lighted match held close to it will do the trick. Replace the switch and test. DO NOT overtighten the grubscrews when replacing switch after testing. Do not throw away your old button cover – transfer it to the new switch.

Older-style Handles:

As above except that you have to undo the knurled ring (may need to use long-nosed pliers) which holds the switch up in its hole in the end of the steel handle and then extract the switch from below by pulling gently on the wires. For the front handles it is easier to unbolt them from the body of the machine. You might have to unscrew the fluorescent light holder and uproot a bit of silicone to get this job done.