The slow feedback kept causing large values of the IMC VCO set frequency, which causes an error for the VCO.  To get around this I turned up the UGF on the IMC VCO slow loop to 0.1Hz, and now the slow feed back gain (In COMM PLL screen) is set to 40000Hz/V.  This seems stable for as long as the cavity stays locked, which is currently a few minutes. I also updated the screen ALS_CUST_COMM_PLL.adl because of a mistake with the reset button.