Shure M91ED - replace cartridge or just get new stylus?

 Hi Folks,

 My son has gotten into my old records, and we have resurrected my mother-in-law's Technics SL-220 which (after cleanup with contact cleaner, new belt, and insertion of RCA jacks in place of captive phono cords) is mechanically functioning well (ie, holds speed).

 The question is: replace the whole cartridge, or keep the current/original cartridge and just replace the stylus?

The current cartridge is a Shure M91ED. We have tried two stylii so far, the original Shure "Hi-Track" (I'm pretty sure the stylus has never been changed and I don't know how many hours it has on it) and a cheap-o Pfanstiehl generic relacement. We like the original stylus better. We have aligned the cartridge with the original Technics "tool" and have moved tracking force gradually up to 2.25 grams (it sounds better heavier, hopefully we're not damaging the records). Neither stylus sounds terrific in my book. Bass is indistinct, and overall the sound lacks detail - it's ho-hum.

The funny thing is that I pulled out my old but almost unused Denon DP-26F and it sounds fantastic by comparison. Tight, solid bass, terrific definition in the highs. This was a cheap turntable in the day. The cartridge (per LPGear it's a Denon MG-2721 MM cartridge) can't be replaced or aligned, and it accepts only one stylus (DSN-81). Tracking force (which we measured at 3.25 grams!) can't be changed and neither can anti-skate.

My preference is generally for "accuracy" over "warmth". I'm hoping for under $300 for a new cartridge/stylus, and under $200 for just the stylus.

Associated gear is nicely-matched solid-state from 15 years ago: Classe CP25 pre-amp with good add-in phono stage, Classe CA-200 power amp, Celestion S300 speakers.

So: replace the cartridge, or buy a new stylus? Or just keep using the DP-26F?

And given my preferences among the few things I've tried above, any directions on WHICH cartridge or stylus?

Thank you for any advice!

- Eric

p.s. I am posting a similar message at another site, apologies if you viewed it there also.