MTR-90 MKIII Transport Servo Alignment

https://drive.google.com/open?id=1BgG4A-g6OOGbmSoK9LYGNKpBO2iNqlZv

i'm wondering if someone can shed some light on the
mechano/electrical alignment on the mtr-90 mkIII
or the
MTR-90III Transport Servo Alignment (J.S. Smulian) included in link above

"With the swing arms at the bottom of their t ravel, adjust the appropriate "M" GAIN
pot on the front of the Reel Control card for 3.0 volts.
If you are using 3M 996 tape, set the voltage at this test point to  2.5 volts."

"The voltage at test points 1 and 6 should change to 6.0 volts. 
If necessary, adjust the appropriate "L" GAIN pot on the front
of the Reel Control Card. NOTE: For 3M-996 tape, adjust the
pots for 5.0 volts."

so what i understand is the 996 is the first generation high level(+6 )
and that these lower settings would relax the tension on the tape
and as i understand it these high output tapes are stiffer and have
slicker backing, seems counter productive to me.

this client likes using SM900 and the like
so does anyone have any insight into what these settings should
be for the even higher output (stiffer/slicker) tapes?

also
what should the the swing-arm spring tension be?
what should the actual tape tension be?

thank you in advance for any helped offered
lance