Scan of manual page that details the spec in terms of ohm readings @certain temps for the pressure reg.
Another check before you drop the pan and filter is to put a hydraulic gauge on the pressure test port of the gearbox. it's just below and immediately forward of the oil cooler ports.
In P N D M4, M3, and M2 you should be developing between 48 and 180 psi, if your on the fringes of 48psi, the box is shot. in reverse the box should develop 60 to 230 psi.
if the box could engage reverse soundly before failure, i'd be looking at the fluid levels and regulator, if it had difficulty with reverse and you find readings on the fringe of the drive specs, the pump is probably shot and if rebuilding that, the clutches are as well done during the rebuild.
Note the two screws described above that shouldn't be undone to get the PR into place by dropping the valve bank, they are detailed in the scan attached.
Sorry took a while to find my manual and sheets - hope you get sorted and continue the E39 strength of population!
Joe
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