Hi @oldprussians my tuppence worth, if I may:
The key EQ issues I found with older MB heads and cabs were three fold:
1) the bass EQ is centred at 40 Hz which is a little lower than I would typically like: 65Hz to 80Hz would be my preference;
2) not surprised that you feel that the treble EQ does precious little - it's centred at 10 kHz which is way too high to be usable and there's a massive EQ gap between the high-mids at 800Hz and the treble EQ at 10kHz;
3) MB cabs have a tendency to roll-off the high end frequencies, which gives them their characteristic "warmth".
Solutions that worked for me:
1) leaving the bass EQ at 12 noon or cutting it, as you are doing, to avoid boominess i.e. almost never boosting it;
2) & 3) using an EQ pedal to boost by about 6dB at around 1.5kHz and 3.5kHz, which is the equivalent of a "presence" switch in other amps - this had the effect of "removing a blanket" from over my MB combos, and made all the difference.