Dead instrument panel and dash lights. Part 2

[Matt West <matt@tdraft.demon.co.uk>]

Thank you for all the replies with suggestions of possible causes of
my dead dash lights.

Today, I have been trying to fix it but didn't get very far.  I found
that the three heater control bulbs had blown.  All the instrument
panel bulbs are OK.  I'm not sure of the state of the auxiliary
instrument (battery, oil pressure and oil temp dials below heater
controls) bulbs because I couldn't get to the rear of them.  How the
hell do you do that ?

All these bulbs aren't getting any power.  I have come to the
conclusion that it may be a fault in the main instrument panel and
probably the dimmer unit.  The dimmer unit is producing a variable
resistance OK, but I can't do much else until I know the pins in the
panel connectors that the bulb circuit uses.
The main instrument panel has three 26 pin connectors on the rear.
Does anyone have a circuit diagram of this unit ?

Matt.
Oxford, England.