Sorry to resurrect an old post but have similar problem and have tried every suggestion I know of from various threads. Monkey recently stopped picking up the ball 100% of the time. It gets real close to the ball but just won't ever pick it up anymore.

Things I've tried.

1. Wiping old grease and re-lubricating the mechanism to make sure monkey can travel smoothly.

2. Putting game in test mode and making sure the playfield magnet activates and grabs the ball as it travels over the playfield. It does.

3. Coil test mode and the coil/magnet does work that actually is supposed to pick the ball up.

4. Making sure the up and down switches test as working as the monkey is in test mode. Monkey does appear to slide as close to possible to near playfield magnet. I know sometimes the down microswitch needs to be bent and readjusted. Tried doing that slightly just in case but seems like that's working fine.

5. Made sure the magnet board sense screws were tight and hadn't worked loose over time. Maybe slightly loose but very little if at all.

6. Tried flipping the magnet sense board but that made it worse. Monkey would only travel halfway down and then go back to castle. Tried flipping board back. Then tried moving the board per threads that sometimes the Magnet Sense Switch needs to be relocated and through trial and area can find a way if works well. This would seem weird sense I've had the game 6 or 7 years and generally the monkey almost always picked up the ball. Anyway, couldn't get this to make it work.

7 After several hours and reading threads on this issue and trying suggestions, in desperation I tried replacing the Magnet Sense Switch and then later the coil with the magnet that is what actually picks up the ball. Nothing!!

Out of ideas and have spent countless hours and not sure of anything else to try. Suggestions, please?

Magnet does activate in coil test but guess I could try testing power to it with a meter. That is if the test isn't an accurate way to see if things are fully working?