Sega CD Model 2 - Freezing during game loading

Picked up a Sega CD Model 2 in tandem with a Sega Genesis Model 2 cleaned the laser lens and checked inner gear function to find the condition to be in immaculate shape with no damage, rail even seemed to have been greased in the past. I'm not sure what else to check for asides from applying more grease to the gears. I don't have a multi-meter, tools or know how to adjust the pot. The system will start up and load normally into a game but the game will not play the game music just the sound effects and when it comes to the CD to load a new scene like a menu the screen will freeze with a black screen and do nothing until the sega is reset. All cables are plugged in however there is an empty cable port (check out the pictures) not sure what it is for.

Model is a MK-4102A

Pictures (click on them to zoom in)

 

Mainboard maybe faulty in someway.

 

This is a difficult repair that will require real tools. You should not attempt to repair electronics without at least a multi-meter. Only in very rare cases will a fix be so easy to not require one.
Your issue is likely related to bad caps or faulty RAM. Could be ASIC corrosion or other things too. I shouldnt have anything to do with your pickup or laser pots. Your pickup passes TOSC and is reading the image fine, the reason SFX play is that they are not streamed off the disc. I doubt your game would load if the lens was faulty, or the music would cut in or out and you would hear/see it "struggling." Your issue is likely logic-level and something else entirely.

-Segasonicfan