Take a look at post “bass response from vintage cartridge « dated 13 Sept. I put some pictures on of a cartridge I stripped open, you might find it of interest.
https://www.vintage-radio.net/forum/...d.php?t=149699
There are other posts on cartridges that may be of interest to you.
You can buy a ceramic bar from RS components.
If you do attempt to refurbish a cartridge you need a delicate touch and a steady hand with good eyesight. All the best.
Cheers
John