I don't see anything about an ST212, but the jumper settings aren't specific to the model, only the type(MFM half-height, full height, 3.5...). You mentioned one of the drives was an ST251-1. The only differenec between the 251 and the 251-1 is it's seek time is about half as fast, and the 251-1 takes one more volt of power than the 251. Getting closer on topic....
MFM/RLL half height jumpers:
(looking at the drive upside down)
Imbetween J1(the long card connector) and J2(short connector) find metal jumpers. The FAR RIGHT jumper is DS1, meaning "Drive select one." if you slip a jumper over the far right pins, in a vertical mannor, you selected that drive as the first drive. the set of pins next to it(the left) is DS2, next to that is DS3, and next to that is DS4. Only have one jumper set per drive. If you set up multiple hard drives in a system, on the bottom of the drive, on the card, is a resistor terminator pack. it looks like a clip that pops into the board. Pop that out if you have 2 or more hard drives in the system!
MFM/RLL full height jumpers:
(drive upside down)
Refer to half-height jumpers for more information, they are the same settings.
MFM/RLL 3.5 jumpers
(drive upside down)
I can't figure out where "J7" is, which happens to be where the jumpers are. But if you find it:
At the very left of the set, find jumper 16. It is the very bottom left pin. Above it is pin 15. If you cover pins 15 and 16, you have the drive set as DS1. If you cover the set to DS1's right, you have the drive set to DS2. If you cover the pins next to DS2, you set the drive to DS3. and if you cover the pins next to that, pins 9 and 10, you have the drive set as DS4.
Again, the terminator pack is infront of J1 and J2, the card connectors, on the controller card. pop it out of the socket if you install 2 or more drives in that system.
3.5 and 5.25 SCSI drives
There are so many pins, I dunno how to descibe it. Refer to pictures.
Pics, in the order listed above:
and the 5.25 SCSI...
So the pics are messy, so what? If you want any diagrams, I have some of those, as well as jumpers for the ST11(M,R) and the ST412 cards.