Thank you in particular for your help and th offer of the loan of your cartridge.
Can I pick your brains some more?
My Rega RB300 arm has the original Linn K9 cartridge which seems to sound OK but rumour has it that it is not good.
Is it worth upgrading and to what.
Yes it is. Depends on your budget and whether you want moving magnet or coil.
It's based on an Audio Technica (it is an Audio Technica) but stylus replacements are not available (there is an AT stylus which sort of fits). The K9 has some value on eBay if you sold.
The RB300 can take a multitude of cartridges, your choice as I say depends on mostly your budget and roughly what sound you'd like.