Mega-CD 1 Slow Disc Tray, PSU Underpowered?

I recently purchased a 3-in-1 PSU for the Model Mega Drive, Mega-CD and 32X, so all 3 can be powered by a single PSU.

The PSU is rated at 9v 3a, the original Mega Drive/CD PSU is rated at 10v 1.2a... not sure about the 32X PSU though.

When I first got the PSU, I only went so far as to test everything powered up, which it did. I only recently tried to play a Mega-CD game. I opened the disc tray and noticed it was opening very slowly. I was a little confused as the last time I used it, the tray opened fine. It was also slow at closing, and would struggle to pull the tray in all the way for disc to start spinning.

Out of curiosity, I tried the original PSU in the Mega-CD and the 3-in-1 in the Mega Drive. The disc tray opened and closed fine and the disc was able to spin. Next, I swapped PSUs around. The 3-in-1 in the Mega-CD and the original in the Mega Drive. The disc tray was again slow to open and close.

So this 3-in-1 PSU is definitely the culprit, and seems to be underpowered to run the Mega-CD properly. FYI.. I have contacted the seller, but haven't heard back as of yet.

Does anyone have any ideas about this? Is the rating on the 3-in-1 PSU too low? It's only out by a single volt, and the amps should be enough (apparently) for all 3 devices at the same time (I don't have a 32X yet). Or is there possibly a component on the Mega-CD mainboard causing this effect on the disc tray when used with a third-party PSU?

Any help would be much appreciated, thanks