> What should I try next to diagnose the problem?
You might be experiencing the infamous Sticky Tailtwister problem. This is
more common in cold weather, but has been known to happen in warmer weather.
Before replacing anything, try rocking the TT back and forth by alternately
pressing the CCW and CW buttons (with brake off.) One to three attempts
should be sufficient -- don't do it a lot or you could break something. If
it doesn't work, I'd try the capacitor replacement next. Also note that it's
possible to move the motor starting capacitor to the rototor side of the
cable, which frees up a pair of wires that can be paralleled with either the
brake or direction leads to compensate for smaller gauge wire.
FYI: I had the Sticky TT problem, as did two local friends. All three rotors
got stuck in cold weather -- mine was like clockwork, sticking any time the
temp fell below 32 degrees F. The other guys were turning much heavier loads
than I was, and the constant rocking back and forth eventually chewed up the
innards of both rotors. Although they tried, Hy-Gain never got to the bottom
of the Sticky Tailtwister problem. It wasn't clear whether it was a design
flaw, a production problem or both. It also wasn't clear whether there was
one problem or two (or three!) They and others were suspicious that the
brake was getting stuck, although there's a possibility that the motor
clutch, which is constructed of cork, was the culprit (i.e., the two cork
disks getting wet from airborn moisture and freezing together in cold
weather.) Some people claimed to have fixed the problem with low-temp
grease. Since my TT was mounted at the bottom of a tubular crankup tower, I
was able to help Hy-Gain test a modified brake design during the coldest
part of our winter. They sent me an off-the-shelf rotor so I could replace
the problem TT and send it in for modification. Meanwhile, I had no sticking
problems with the replacement TT. Unfortunately, the modified TT stuck just
as badly as when it was unmodified and Hy-Gain was back to square one. They
let me keep the replacement rotor and it's worked fine ever since. Note that
Hy-Gain programed the DCU-1 digital controller to do a single rock by
turning the rotor opposite to the desired direction briefly at startup.
I happen to have a couple of Ham IV rotors and they have worked fine
year-round, too. I've heard sketchy reports that they can stick, too. Both
are on crankup masts, so all three of my Hy-gain rotors are easily
fixed/replaced. If I was buying a rotor for the top of a tower, it would not
be a Hy-Gain!
73, Dick WC1M