I hadn't noticed a clip was missing. I couldn't find it, but found my cam locks have the same kind of clips, so I grabbed one of those and it seems to work fine. In testing this, I found one of the racking adapters has a small crack (see picture here). So, I'll take $5 off the price of that...
I have some miscellaneous equipment and better bottle fittings that I no longer need. If you're interested in purchasing any of them, let me know.
Deluxe Counter Pressure Bottle Filler - $50 (cost for a new unit is $90)
Carboy Handle - $4 (new one costs $9)
Misc. 'Better Bottle' parts...
Perhaps you got an old unit with a low battery. Maybe try putting in a new battery. As schmurf stated, you shouldn't attach anything to the Tilt, as any kind of weight on it will further skew the reading.