After the first "energy crisis" in the1970s drove up energy prices, a bunch of engineers petitioned the FCC to allow them to not have to burn off extra power as heat to reduce efficiency with what was variously called a Series Limiting Resistor, a Linear Resistor, a Power Dissipating Resistor, Efficiency Resistor, etc. The were allowed to input like 3500 watts, 3800 watts, 4200 watts, etc., instead of converting 1500, 1200, or 800, etc., into heat, but still license it at the 5000 watt nominal power. If they had to move, or otherwise relicense, they were required to use the actual input power as the licensed power. I suspect that that is what happened with WMBI, that it actually was 4200 watts all along, or thereabouts. If the APP was online, we could verify this.