TOPIC: Shipmaster control unit - detent ball

Bought a used Shipmaster controller. There seems to be a detent ball behind each lever. Has anyone replaced one of these detent balls?

Pics of the balls would be nice...maybe that should be rephrased.
Are they plastic or steel ball bearing type? If you're having trouble usually a good cleaning of the old grease should suffice.

It's a hard plastic button with fairly stiff spring action behind it. Gear lever works fine, but the trottle lever works smoothly fir a few movements, the catches and requires a little extra force before it starts moving smoothly again. It also makes a dragging sound and I found a small piece of the plastic button in the housing. I'm wondering if it really needs a detent, the cable has some drag in the sheathing.
Here's a pic of the good lever, with detent in good order.

Throttle lever and housing with detent notches.

Throttle lever and housing with detent notches.