What's a real good arm for a Decca Cartridge?

If your alignment is *close* to correct it is likely not the culprit. How much does your 'dressed' headshell weigh now?

I would guess around 26g.

Here's a weird one. I swapped out the 3" maple shelf I had installed on my wall shelf just a month ago and went back to the 1/2" maple shelf I was using before and it has only misracked once since then in two days of listening. Either the rigidness of the thicker shelf was bad or somehow there was something wrong about how the table was sitting on the thicker shelf, even though I checked and rechecked the leveling. 

Hmm. Higher self resonance frequency for the thinner shelf? Interesting indeed.

A word about Trans-Fi linear tracker.
 All my higher quality cartridges, both very low compliant and very high compliant can do all the Telarc 1812 Overture cannons because the Trans-Fi  arm is capable. But only a couple of them can do the very last cannons with an authority that leaves me speechless. Trans-Fi T3Pro is able to distinguish true tracking ability with ease and obviously the true very finest cartridges. I don´t have a Decca Jubilee not to mention the Reference but my friend also runs a T3Pro and hasn´t had issues with his Jubilee. Trans-Fi linear tracker does the job.

While we are on the subject of Decca.

Does anybody know much about Decca London Blue, supposedly rebuilt by John Wright?

Sound to expect?
Might work out on the Nottingham table which has a fairly decent unipivot arm.

Or even on a Lenco......

Always been intrigued by them but no experience with them at all.