Batboard

I am having a low deviation problem on our msr 2000 VHF base station on tx. The service manual gives a fix as replacing Q501 on the exciter board to correct this. Well it did not work, also I swapped the channel element and had no change. The max I can get out of the unit is 1.0 of pl dev and 3.3 out of the audio path at 1k signal in. Any ideas?

Thanks.