The pre-wash dispenser cup opens OK but the main-wash dispenser cup does not, it seems to be very hard to manually open compared to the pre-wash unit. Not sure if the problem is in the whole unit of the detergent cup dispenser or if the unit can be taken apart and cleaned, or?
I have replaced the bimetal housing on the the pre-wash unit and the main-wash unit bimetal housing looks OK by eyeballing it.

PROBLEM SOLVED

Steps taken to resolve problem.

1. After removing the door panel, checked the four electrical connections on the cup dispenser for live/hot connections on the dishwasher which was turned off, none found so continued. Some may want to follow the diagram instructions to turn off the circuit breaker but I was comfortable doing my process, besides, I can't see in the dark.

2. Removed the complete detergent dispenser-easy peesee. The diagram doesn't show or mention that there are TWO bimetal housings and I had just previously replaced the one for the pre-wash side which probably wasn't bad so I saved the one replaced. The pre-wash side plastic flap seemed to be opening after this was replaced but the main-wash side flap was still not opening.

3. I checked the complete detergent dispenser for any "stickiness" but found that both flaps moved OK, no "stickiness".

4. Reinstalled the detergent dispenser and replaced the bimetal housing on the main-wash flap with the old one from the pre-wash side.

5. Fired up the dishwasher and ran it through a complete cycle. Results: both flaps working OK, opening at correct time in cycle and no leaks.