I managed to get the HT pick up away from the mag (without removing the oil tank and pipes). This was easier than I first thought....for once.
My query is as follows. Using a multimeter continuity test, should I be able to get an audible bleep if I attach one lead to the carbon brush and one to the internal metal bit of the pick up (where the HT lead is usually inserted)?
Yes you should have continuity between the spring loaded brush and the tinned raised brass segment at the bottom of the threaded part of the pickup. You may have to put some pressure on the pickup brush spring to get a reading. If not pull it in bits and clean it all, clean off scale on the tinned part down the threads of the HT connection and try again.