The nominal power is 100W out of the IPA (STXe 500 Exciter), this value is hard-coded in the software and can't be adjusted.
If there are Power Supply failure(s) the output power rolls back in the Exciter. Here is a list of the expected power on the Exciter depending the number of bad/faulty +52V Power Supply;
1 Bad Power Supply = 70W output
2 Bad Power Supplies = 50W output
3 or 4 Bad Power Supplies = 35W output
If the Power Supplies in the STX 10 are not the problem then it will be necessary to set the STXe 500 as a stand alone exciter and test if you can actually get the full 500W forward power into a 50 Ohm dummy load. Possibly the final Mosfet Transistor could be damage in the RF Pallet reason why it cannot reach the desired 100W forward power.