Eric,
The antenna from RS is probably OK, and you are just loosing signal from the conectors, also how is the RG6 connected to the antenna?, Most RS antennas (multi-element Yagis)are set up for 300 Ohm lead, you will need to install a transformer to convert the 300 Ohm to 75 ohm of the RG6. A few mor notes re the RS antenna:
Yagis are VERY directional, they have well known patterns, and unless most/all of your stations are comming from one area, you will want a rotor. Unless the Yagi was designed for FM ONLY, it will cover the VHF spectrum (TV chnls 2 ~ 13; this should not pose a problem, unless you are having multipath and sensitivity problems. The suggestion of the MD ST-2 whip antenna is a good one, as it is omni-directional.
good luck.