Phone II hummmmm

Hi, all.

I've recently changed the MC transformers (from the standard 1:20 WAD) in my Phono II as I needed a bit more gain on my new cartridge (Goldring Eroica Elite).

I've fitted some Lundahl LL1678 configured for 1:32 step-up. Apart from that the amp is as per the original design.

Now I'm getting quite and audible hum which increases if I touch the headshell on my Rega Planar 3. The Rega earthing is supposed to be via the shield on the phono cables and the set-up as it was with my previous cartridge which didn't have any audible hum.

The hum decreases if I touch the headshell and the body of the pre-amp at the same time suggesting that the earthing from the deck to the amp isn't working. I've twisted the input wires to the transformer (as per the original WAD installation) and I don't think the hum is being picked up there.

Has anyone else had a similar problem with the Rega arm/deck? Would it be ok to create a seperate earth from the deck to the amp and does anyone have any suggestions on where is the best point to attach it on the deck?