If water gets in there with power on it can raise all kinds of havoc with the amp.
On a side note: How is the over the air reception where you are?
Is it possible there are NO stations to receive?
Remember that all most all TV broadcasts are now DIGITAL. If you have an older TV (NOT digital) you will NEVER receive a TV signal. You MUST have a digital to analog converter box to watch over the air TV now (in both Canada and the US).
Also Digital TV uses "primarily" UHF, BUT there are digital VHF stations as well. Digital VHF stations are directional. Aiming the antenna is critical to good (or sometimes any) reception.
Some great threads on the subject:
Winegard wingman antenna booster
Digital TV confusion
Use this web site to find the POSSIBLE broadcast towers in your area and the direction to aim your antenna here: http://www.antennaweb.org/
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW