I finally got out to the shop to take a closer look at my
MC-60's. The resistor in question is a different value on both controllers. One board is marked Rev J, one is marked Rev E. Funny thing, R42 is clipped on one end on both boards, and the resistor is bent up vertical to the board.! It's not used! Both boards are in service, and both function flawlessly. The Rev J board has R42 in the same position as yours, Rev E board, R42 is near center of the board, on the right side of the big power resistor. Both resistors ar 1/4 watt. Both boards have the label RPS1 next to R42.
I found somewhere on the web, a description of how to defeat the soft start on these controllers. I tried the mod as described, but it didn't work. It involved removing a transistor, if I recall correctly. I reinstalled the transistor. I wanted to be able to set a speed on the mill, and be able to shut it of and restart at the same speed again. Now, I just live with the soft start. It requires turning the speed pot to zero and back up untill the motor starts, and then setting speed. Works the same way as my 7x lathe controller, so I guess it's a good thing, plus I'm used to doing it that way.
I disconnected the muller controller and brought it in side to look at under my magnifier. It's (Rev E) R42 is banded brown, red, black, green, green.
Guess I'm not much help, eh?