Low Volume from right speaker of ent...

Hi There thanks for your very good desctiption of the problem it really helps to have a lot of detail...

There are Mono and stereo types of stylis cartridges and it sounds like you have a mono equipped into a stereo amplifier..

If there are 4 small coloured wires visible under the stylis then
its a stereo stylis and should work, have a close look and maybe one of the small wires has dropped of the small pins on the back opf the stylis cartridge.

If there only two wires visible then its a mono cartridge and this is why you only have sound from one channel..

So answer is wires dropped of the stylis.
or
Wrong type of stylis cartridge.
or
if there are four wires and thay all look connected then perhaps the stylis is faulty and you need to replace it...

Cheers from YU BEUT