After decades of being a Tele guy, I decided to make a change away from hard-tail. I went all the way to an Ed O'Brien Strat with a Fernandes Sustainer system.

I'm still on the first set of strings, which the Internet tells me should be 9s, and I'm finding that some strings are not being "caught" by the magnets to the extent I would like. Specifically, the B-string response is weaker than I would like.

When in sustain mode, it pulls from the Seymour Duncan JB bridge pickup and sends signal to the Sustainer in the neck pickup. There is a switch that allows the choice between reinforcing the current note and I've octave up, or a mix I don't understand yet.

It's the low strings that I find work the best, so I'm thinking that thicker strings, maybe 10s or more, might work better, getting more metal for the magnets to grab. In the other hand, I could imagine thinner strings like 9s and 8s having less mass, providing less inertia for the mechanism to override.

Between the Sustainer and the E-Bow, driving strings with magnets is a decades-old thing so these questions must be answered, but they never have been a major thing, so the answers are not common knowledge. Hopefully, someone here knows.