Anything I should know before buying a Micro Seiki RX-5000

If you're buying ones with vacuum hold down feature, make sure the platter seals are in good shape. New ones can be bought (TechDas uses identical seals), but are pricey. Vacuum pump  and as lewm mentioned, motor health. AFAIK RX-1500 uses FG servo controlled DC motor.

Sorry no experience with the 5000.

I was only interested in non-vacuum hold down for fewer things to potentially go wrong

Firstly, be thankful you have the opportunity to buy one. These were lifelong purchases and do not appear often. Have the power supply recapped if required (mine is still fine from 1980) and install on an isolation platform, setup a few different arms and enjoy.

Micro Seiki made some attractive turntables performing at a high level. Pride of ownership is easily understandable.

@hvbias - Good luck on your hunt and hope maintenance will be reasonable.

If money or space weren’t an issue, I’d love to own a Micro Seiki SX8000II….in top working order. 

Greetings.  I own and have restored 6+ of the MS 1500/5000s and they are one of the best "future proof" decks out there.  No ICs to go obsolete and very easy to service.  Motor bearings are standard size metric oilite.  Key item is selecting the proper spindle lubricant.

The pumps will always need all the hoses replaced if it was not done already, and, if needed, I have replaced the pumps with modern pumps, a relatively straight forward exercise.

Good luck, these are great tables!

Kevin