[Heathkit] need help on a sb-301

[yash at aol.com]

                           Started earlier this week with a really rough 301,did a full cleaning on the chassis, touched up all the switch contacts with dexoit,went thru all the tubes and replaced a 6au6, all the rest looked fine. Replaced all the electrolyics that looked bad saw nothing else burnt or out of place. Fired the rig up and every thing worked as it should ,but very low sensitivity. I did a complete alignment on the rig and she really came back to life. My only problem is that when tuning in a station,usb or lsb,the rig acts like you had the agc off. the signal is loud and distorted,if you VERY carefully tune can get things somewhat clear but not good. backing off the rf gain changes nothing, subbed any of the audio tubes ,no change. The agc circuit seems fine . Have not done any voltage readings as of yet. T have a second 301 in a set of twins that works fantastic. Can any one give me a starting place to check on the 301  to maybe narrow the problem
thanks for any help.
dale wt4t