It turns out the thread guide on Mary’s new Juki TL-2010Q sewing machine has what’s euphemistcally known as “negative clearance” with the ruler foot she uses for quilting patterns. With the foot raised to move the cloth, inadvertently pressing the foot pedal or turning the handwheel can crunch the thread guide against the foot.
As you might expect, the intricately bent wire thread guide doesn’t survive the encounter. Not having a spare ready to hand and not knowing quite what it should look like, I reshaped it as best I could:
It worked moderately well:
The automatic needle threader wasn’t reliable, but she could cope until the replacements arrived.
Comparing the new one (left) with the wrecked one (right) shows I didn’t re-bend the loop tightly enough, putting the end on the right at the wrong angle:
It’s the kind of shape you can duplicate by the thousands with a production machine, but can’t make at home without entirely too much tedious effort.
The new one works fine, seen here in front of a walking foot, with the auto-threader looming in the upper foreground:
Aaaand now we have spares!