Firstly caution with the marpet upgrade. The problem with them is it can cause the the pins on the MMU to be bent out and not make full contact with the chip inside.
This actually happened to me and the computer shop said nothing we can do. a few years later I found out what had happened and managed to bend the pins back (only by a little but enough to make a firm contact).
Also mount a piece of cardboard on the solder side of the MMU adapter to save a shorting problem there.
I would say pop it round and I can check it out with the oscilloscope but I guess your quite a way from suffolk?
