Colin: I have just completed a 100%
rewire of my 69ish TR6. A Dan Master
Power Block wire harness with on-site
help from Dan's son Mike. All new lights,
switches, etc.
Some problems still came and went at random. Dan
told me my TR originally had a strong ground wire
from the engine block to the body metal shell at the
firewall.
My firewall is bondo and fiberglass so today I ran a
No. 8 wire from the negative battery cable/block
connection to a spot on the wheel arch I stripped down
to white metal. Used a lock washer to grind the connection
into the sheet metal after I coated everything with that
dielectic muck.
That heavy ground wire seems to cleared thing up
in a hurry. Photo attached.
Hope this helps ya.
d