Instead of looking for the person at PSE&G who never returns my calls or emails, I called a more general number and got somebody who actually seemed to have a feel for what's going on (after opening my file). The long and short of it is that I'm now convinced that the solution lies with my installer, not the power company.
It was mere luck that the ancient electric meter was capable of net-metering. Nobody at PSE&G seems be be convinced that it has that capability. The installers sure knew. I remember how we gathered around it and watched the dial spin backwards.
At any rate, though, PSE&G sounds like they're pretty close to cutting the order to install the meter I need. They still need this Part B thingamajig from groSolar, though. So my next task is to talk with them (they're in Vermont, I'll bet they'll be nice!) and ask them if they ever filed this form, and/or if they happen to have a copy, and/or if they'll do a new one for me.
I expect they'll say "No" "No" and "Yes." Hopefully somebody will be willing to fill out and sign a new form, which I can then fax to PSE&G and end this nightmare...