Dancing Cartridge.

In the case of the original (Ortofon OM5e I believe?) you have a cartridge compliance of 20 and the Tango is 12. Probable mismatch of cartridge and tonearm. The Grado's compliance is also 20. However, Project owners have complained about poor performance with Grados, you're not alone. A search of other forums will turn up several threads about this mismatch.

I've had some similar experiences with a Pro-ject Expression table using an Ortofon 2M Bronze, usually when the musical passage gets really complex on orchestral music. I've had no problems with the same table using a 2M Black or a Goldring 2500. I think the problem lies in the Pro-ject's arm lack of damping, which might make some cartridges with larger stylii (the two you've mentioned both have elliptical) jump around from arm vibrations. My 2M Black and Goldring 2500 have smaller, better-tracking stylii. You might try some tweaking of the arm such as wrapping it with teflon tape to see if it helps. Make sure your stylus force gauge is accurate and set the force to the high end of the cartridge manufacturer's recommendations (although you've probably already done this). If still no luck, you may want to try a cartridge with a finer, better tracking stylus. MM is the cheaper way to go. BTW, the Pro-ject's underdamped arm may also be responsible for its lively and exciting presentation. I've got a room full of tables and arms and cartridges--some costing thousands--and I've had a blast the last few months comparing it (often favorably) to the big boys. IMO the Pro-ject rig deserves a high quality, great-tracking MM cartridge; but be cautious and buy used, in case my whole theory is wrong!

Thank you both for your quick responses.The original cartridge that up to this moment is the only one that does not vibrate is a Sumiko Pearl I believe.The Ortofon Tango has a Fine line stylus on it.Dlshifi,what cartridge are you using on your expresion.I would love to have a good MM on my turntable , my problem is that my Preamp, Audible Illusions has the John Curl optional gold phono board specifically design for low output moving coils.Together it with the line stage has a 90 decibel gain,(30 on the line stage and 60 on the gold phono board)When I use a MM or my own grado black I'am overloading the phono stage to the extent that I can't pass the volume control past the 9 oclock position.This leaves me with no other choice but to use a low output design.I.ll try some way of adding more mass to the tonearm to see what happens.By the way,the project is in sonic terms a run away bargain .I've got the project speed control unit which made a big diference.I'll report latter after my experimentation adding mass to see if it keeps doing the Fred Astairs rutine.