my RB pro S
pin does not protrude but sits flush (ok recessed 0.1 mm) at both portrait and landscape,
except when the shutter release is depressed
if the body is not armed it only extends 1.0 mm
if the body is armed it extends about 5.0 to 7.0 mm
I'll use a gauge if you need more exact?
Im confused on my Pro S
- When the body is armed and the pin should comes out its 4.5 mm the back will physically stop the pin before that at about 3.0 mm? This blocks the shutter stopping a double exposure
or
- the rotating adapter will block the shutter release if the dark slide is not out, the dark slide has two fingers which tell the rotating adapter a back with a dark slide fitted is present the pin should come out 2.0 mm
You need to check both cases
I apologise I was abstract an old computer disc drive is a good source for springs if you dismantle it if you can't get the correct one from Mamiya.
There is a repair manual
google MAMIYA RB67 repair manual
my phone won't pick up the PDF URL sorry