Sounds like your springs may be losing strength or your drive gear may be wearing. Take off the cover and look around the front of the motor (door side). You will see a white nylon gear. Look for wear and possible white saw dust. If the gear looks okay you will find a control on the end where all those white wires go that is marked 'up force'. Increase it about a quarter turn and try the door.

I removed the cover and as I was doing it, my vibrations were shutting the entire GDO off and on. Keypad, lights and sensors together were clicking on and off as if I was pulling the plug and plugging back in. I tried opening the door and bumped the housing and it shut off. I hit it again and it came on, etc, etc. I did see some wear and white sawdust on the nylon sprocket but not enough for replacement (I think). Because it sounds like a microswitch is tripping in the circuit board, I unplugged and removed the wires and then the circuit board. Can I get a replacement for a decent price?

Sounds like you have a bad connection somewhere. The price of the board runs about $80.00 but I wouldn't do that. Once that gear starts shedding the white sawdust it is a one way downhiull street.

So if the gear is toast, is it worthwhile to replace it? Or is it better to get a new motor unit? rg

Here is a link that might be useful: Gears

Bad drive gears are among the most common problems with openers. If it is a newer unit I would replace it (the gear), if it is older it might not be worth the service and labor charges to replace it.