1958 Grundig 8058 PE Rex w/ mag cartridge

[omegaman]

I got this Perpetuum Ebner Rex Deluxe changer in a Hi-Fi Console Grundig radio

It came with an early magnetic cartridge

The changer works great mechanically but it doesn't sound as good as I think it should

I recapped this whole receiver
The radio sounds fantastic

The record player sound is all garbled in bass and not as it should be. I put an inexpensive stylus in it but it never sounded right

I de-oxit'ed the cartridge pins and connections
I tried the changer plugged in to another receiver and it still sounded poor

Any ideas to check with the amp?

Where do I get a replacement for this cart?

I ordered a new stylus again, to rule that out

Basically, how do you check a cartridge?