[ICOM] ICOM_746PRO_ALC_PROBLEM

[George]

A friend asked me to help him try to find out why his 746PRO ALC cuts off his SSB transmission for the first second or two while the ALC drops down from 100%??? 
This only happens when we have it running into his Ameritron AL811 amp??? 
This does not happen when we hook up his backup 746-non pro rig???
The ALC on the pro seems to have a very slow decay time as compared to the non pro 746. Why does the pro ALC jump to 100% intermittently when used with the amp. It's very annoying to say the least and rendered it useless.
Has anyone else experienced this?
thanks.
George  W2YJ