wiper delay

I am fooling with the wipers on my 77 this morning. Symptoms are:

When turned on and right back off, it makes two swipes. Usually.

When turned to slowest delay, it initially works just fine-perhaps 5 cycles; after that it often goes to a slow drag across the glass with no delay between cycles, just really slow. Doesn't always do this.

Sometimes slow to park

After being in on position for a while and then moved to delay, it doesn't wipe without resetting the switch.

Everything works fine in on position and both speeds work fine.

It is more annoying than anything. Is it likely the motor, the switch, the signal intensifier?

Any thoughts?

Thanks,

Leonard