After reading about various solutions to the spindle-lock on JET lathes, here is my solution that frees up both hands. I have a JET 1442 lathe.
I removed the U-shaped metal guard and replaced it with an S-shaped piece of cherry. I used the original tapped holes to attach the piece of wood to the lathe. There are no loose parts to misplace and no parts dangling on a tether.
Not only does the pivoting arm hold the spindle-lock button depressed, it holds the power switch in the off position. I cannot turn on the power before releasing the spindle lock.
~ Frank Pickett