The SB-220 I repaired for my Ex was a bit touchy tuning... I use to grab the knob skirt and roll my finger along the front panel to tune it slowly. I have to agree with Steve the cabinet is a pain to get on and off. It does go on easy enough by placing the amplifier on it's rear panel on an older copy of the ARRL Handbook and slide the cabinet over it, line up the holes and put the feet back in. If I ever get one the first two things I am going to do.... Make a wiring harness for the front panel meters and controls that will unplug. I will also make a dummy panel with tuning holes in it for the input circuit coils.