i bought my first bass(brand new) this weekend and picked up an old peavey amp off of craigslist. The amp sounds good, but when i plug in my guitar to the low gain input somtimes i have the wiggle the cable connector to get a good connection. Also on the high gain it works 50% of the time, when i stick the plug in slowly i can hear it make a connection, but once i stick the whole plug in it wont work. Does this sound like i just need the jacks to be replaced? Or do you think it might be something else? HOw much should i expect to pay for this service? thanks