I'm obviously not MODOK, but he hasn't been frequenting the boards as much, so I'll share my experience:
Load can be tricky depending on how your exercise selection works out.
First off, my load is always determined by a +1/-1 principle. So today was a 13-15 rep day. I chose a weight that I felt that I could do 12 reps with for my first (top, maximal) set, and I try to hit the 13-15 range. As long as I am within 1 of the rep range, then I keep the weight for the next set. If I'm further off than that, then I either drop or add weight accordingly.
Now, to choosing load:
IF you do an exercise more than once a week, then it's pretty easy. So with squats, which I do 3x/week, I will often just take the weight from my 10-12 day and move it to my 13-15 day the next week. In other BBB threads, one guy (SmallToBig) advocated using the 8-10 day weight for the 13-15 day the next week. I just don't find that I progress at that rate.
I really like doing exercises more than once a week. Working one exercise in the 13-15 range and, say, the 8-10 is a useful way to progress. If you don't do it that way, then go off the indices that you see from your other exercise choices during the week. If you get stronger on a lift, then expect to be better with the other.
Warning signs that something is not going right:
First, focus on your top set--i.e., that first set. If your top set isn't where it was the week before, then that should be a concern. HOWEVER, this has to be put in context. If you're on the third week of Ramp2 6x/week, then you might see a drop off in weight that week. Just power through the week for SuperGrowth, and eat a lot.
If you feel like you don't want to go to the gym during the first week of a ramp, then you should probably do SG for a couple more weeks.
The 'try as hard as you can' mantra is expected to do a lot of the work. You should always be really pushing the issue, using the SG periods to get some rest and allow for the supercompensatory effect.