[BigLew]

The antenna may have taken a whack or if old enough, it's core components may have come undone in some fashion. Do you have a friend that you can demount the radio itself and hook up to his good antenna for testing? Where was the radio stored over the winter and could it be damp on the inside enough to have condensed humidity for a droplet that is shorting out part of the circuit? Is it receiving? Is the mike working and can you check it out on another radio of the same brand/series; maybe not because a lot of the recent units have a hard wired mike that cannot be removed.
do you have a friend that has an SWR meter to determine if the radio is putting out any sort of signal? (The SWR meters used to be around when CB radios were popular and someone you know may still have one lying around somewhere.)
do you have a friend or family member into ham radio that might give you some help. (Also there are a lot of ham radio clubs around and I'll bet there is a member in your local club that has every radio testing device known to man sitting in his basement. he'd probably jump at the chance to fix yours and show off his technical EXPERTISE!) Just a couple of my free ideas.

Now for those with the price tag.
Your local marine electronics service business,
a new unit (if the radio costs less than $250 and is three or more years old it is probably cheaper to replace it.)

Good luck.