I guess the first thing is, have I identified the correct remote?
I concluded you needed a Technics RAK SC508W from this manual, which shows it on pg 4:
If that is the correct one, then the one on Ebay looks original and the same as in the manual. They claim its in perfect working order so it should be fine. Worst case you would need to return it for a refund, which I know can sometimes be a pain.
I hope that helps.
Best Regards, Richard