This remote should be the correct one for the 510….
https://www.ebay.com/itm/PIONEER-CU-V11 ... 632-2357-0It is really just a basic remote with no key changer control because the 510 was one of those odd karaoke machines that had no key changer built in but instead had a loop through option to add an external one. So essentially speaking, it’s just a machine with built in mics and a multiplex balance knob.
The remotes mentioned by tasuke should be fine too and are obviously cheaper.