'07 DC - JBL amplifier problems/replacement?

Hi All -

Today I got in my truck and the stereo sounded funny. There was very little low end and the whole thing just sounded kind of phasey and odd. I fiddled with the audio controls and still could get no low end out of the system so when I got home I cranked the passenger seat all the way up to check out the cabling to and from the amp. No loose wires, no melted plastic, everything seemed snug and no amount of jiggling resulted any change in sound. I decided that everything was fine and continued my investigation to the sub itself. I couldn't tell if it was silent or just way too quiet so I unbolted it from the floor to have a look.

Upon visual investigation, I could see the cone of the sub moving so I decided to crank the volume to see what happened. It seemed like something in the amp started clipping out because occasionally there was an occasional harsh clipping noise coming through what seemed like all the speakers in the car with the volume maxed. Whenever this noise occurred i could visually see the sub pumping quite a bit.

So what we know now:

1) sub is getting signal
2) all harnesses and connections seem good
3) same sonic problems are present regardless of input source, so problem somewhere later in the chain than the HU

This leads me to think that my actual power amp has gone bad. I have found a replacement for $150 free shipping online. Should I just go ahead and order it and throw it in to see if that fixes it? Is this a known problem with these earlier JBL factory systems? I'm thinking problem has to either be bad amp or somehow a cable has gotten loose or frayed in just the right way to short circuit the amp to some degree... hoping to god it's just the amp because wiring sucks to fix...

Any ideas greatly appreciated.

Colin