Wiper Problem

I've got a 63 convertible that is having a pretty sporatic wiper problem. Sometimes they work . . . sometimes they don't. Not working consists of two problems:
1) Turning them on. Every once and a while they just won't turn on, then a few miles down the road they start going.
2) Turning them off. When I do get them on, they don't exactly go off when comanded. I know the motor needs a rotation or two to get back to the off position, but they keep going, and going, and going.

I purchased a new wiper switch thinking that this was the issue, but unfortunately that didn't work. The motor works fine when you get power to it, so I don't think the motor needs replacement. I have resolved that there must be some grounding issue. Has anyone come accross this problem? Where are the grounds for this circuit. Anyone got a wiring diagram to share?

Best regards

Hi farmetr, there are two grounds, one on the wiper motor which should connect to the bellhousing, I think it was a black wire but i'm not sure of the color.
And the second ground is from the wiper switch, try grounding the switch with a jumper, if it works just connect it perminately.PG.

Wiper relay is my guess, and yes, check the grounds.