You should bond your mast and coax shield to ground for safety reasons as well as reducing undesired signals present on the coax shield. The exact method required in your jurisdiction is governed by the local electrical code.
Having said that... As a test (And for safety reasons, a short, temporary test) Running a known good coax directly from the antenna to a known good receiver is a good place to start.
The goal would be to determine if the splitter or coax disconnected during the test is causing part or all of the problem.
Pay close attention to signs of moisture, corrosion or looseness at connections. Also look for kinks or sharp bends in the coax.
The CM 4221 is not designed to receive VHF channels. The HD7697 on the other hand should be
PLENTY of antenna for your situation.
A second thing to consider; If possible, try experimenting with elevation and small aim point changes.
Best regards
