Trying to troubleshoot a problem with an AC Motor and Drive

I am dealing with some rather ancient technology, a Powermaster variable voltage unit which appears to be original (1975) seems to be set at 50% (input voltage is approx. 225 and output is 117) that is controlling voltage to a Fuji AF-300E$ Drive unit. This drive (as near as we can tell without schematics) is controlling one and possibly two motors in one machine (a product cooling spiral)
The drive is putting out 30 Hz, 115 - 118 VAC at 2.4 Amps to our motor which it is reporting turns at 900 RPM with a torque load of 18 to 20. Our conveyor motor (circa 1975) is name plated 1/2 HP at 230 VAC and 1745 RPM turning a 30:1 gearbox. The second motor, that the drive may or may not be controlling, rotates the inner cage (was replaced in 2021) and is name plated 1 HP at 230 VAC and 1745 RPM turning into a 60:1 gearbox.
The 1/2 HP motor has recently began to stall out briefly under load which stops the conveyor, but the cage continues to rotate. When monitoring the drive during a stall, the voltage, amperage and even motor torque all remain relatively unchanged. I am trying to figure out if this is because the drive is simply reading the larger motor so the stall out isn't noticed. The 1/2 HP will restart itself but there appears to be no change in drive output...
I increased the output Hz on the drive to 30.2 and boosted the Powermaster to 60% which seems to have stopped the stall outs for the time being but I would really like to make sense of what I have and how I can improve the operation long term.
It would be good for you to provide a drawing of the electrical circuit you currently know and possibly get someone to trace out the rest of the circuit safely with the power off so we know what you are starting with. If you still need help, provide full part number of the drive. From what I have seen in the drive manual the largest size 110V drive is 1HP, so I wouldn’t expect 1 1/2 HP of motors to be connected.