Hello. Happy New Year. I bought this device and fixed it. It was very dirty. It was left with batteries for a while, so all the contacts in the battery compartment were rusty. I had to remove them. Instead, I installed a li-ion battery. I washed everything, cleaned the inside. New belts were replaced, maybe someone will need them, the main diameter of the first deck is 74 mm, thickness is 1.2 mm, the dial is 56 mm and thickness is 1.0 mm. The second deck is 71 mm, thickness is 1.2 mm. Everything works great, appearance is 8/10, one switch knob is missing. The sound is great.Unfortunately I couldn't find a service manual anywhere.
Very nice! I'd put these and the big Pioneer SK-61's (the whole series) as the biggest, baddest boomboxes ever. It's too bad Sansui didn't have a late 70's statement boombox. I think the internals are mostly the same for the 4000 Series, I've seen something for this model but can't find it now. Here's the 4503 manual: https://elektrotanya.com/supercope_marantz_crs-4503s,l_sm.pdf/download.html I had issues with the isolation washers, they're tiny and if your not paying attention they slip down into the mechanicals. Without them you'll get a grounding buzz.
