Universal Sonar: No more temp, and (now) weak signal

For Christmas, to my astonishment, my wife got everybody to contribute
to the topmost item on my wishlist, a Minn Kota Maxxum 65, and she even
(accidentally) got the upgrade US (Universal Sonar) model.

So I replaced the CRUMMY old stock Evinrude 20 something pound thrust
on my boat, and everything was perfect... well almost. My bow-mounted
Garmin 240 used to have temp when I had the Garmin puck transducer
mounted to the old trolling motor, but it seems the Universal Sonar
doesn't do temp. This is actually a pretty big disappointment,
especially since that was the only thermometer on the boat.

I know at least a few people here must have experienced the same thing,
and I'm wondering what solutions you came up with.

One more thing: Last weekend my sonar was showing a very weak
signal--the bottom was so faint that it couldn't calculate depth
automatically. Also, bottom was the only thing I could see (and just
barely). No chance I could discern structure, balls of baitfish, etc.

I adjusted the contrast, though I knew that would do no good (and it
didn't). I tried raising the motor and splashing it down to get rid of
any potential bubbles on the transducer surface (US transducers are
mounted in an inverted "well"), and I don't suspect that was the issue,
either. Also the clicking of the transducer *seems* as loud as ever.
Also, I reconnected the sonar plugs to make sure that the contacts were
good, but they look nice and clean, and reconnecting didn't affect the
signal at all.

Anyway, I've still got the old puck transducer, so I could do some
side-by side transducer testing, but wondered if there was anything
else I should check.

Thanks!
Jamie