Thanks again everyone.
Here's all the circuit stats of the new switch.
Key in OFF position
M-R OPEN
M-S OPEN
M-B OPEN
M-A CLOSED
R-S OPEN
R-B OPEN
R-A OPEN
S-B OPEN
S-A OPEN
B-A OPEN
EARTH-M CLOSED
EARTH-R OPEN
EARTH-S OPEN
EARTH-B OPEN
EARTH-A CLOSED
Key in ON position
M-R OPEN
M-S OPEN
M-B OPEN
M-A OPEN
R-S OPEN
R-B CLOSED
R-A CLOSED
S-B OPEN
S-A OPEN
B-A CLOSED
EARTH-M OPEN
EARTH-R OPEN
EARTH-S OPEN
EARTH-B OPEN
EARTH-A OPEN
Key in START position
M-R OPEN
M-S OPEN
M-B OPEN
M-A OPEN
R-S OPEN
R-B OPEN
R-A OPEN
S-B CLOSED
S-A OPEN
B-A OPEN
EARTH-M OPEN
EARTH-R OPEN
EARTH-S OPEN
EARTH-B OPEN
EARTH-A OPEN
I'm hunting the wiring diagram now.
Cheers.