Why aren’t my subs hitting as hard as they used to?

A reader recently wrote it to me with this dilemma.  Tommy writes:

Hello, I’ve been searching the internet for answers why my subwoofers problem. I have been running this set up i bought from this website for one year.(http://www.crutchfield.com/p_700MRPEBB/Alpine-500-watt-Dual-12-Bass-Package.html?tp=442). Now, for the past 3 months, these subwoofers havent been hitting hard as they use to. I agjusted the gain higher than normal and it still doesnt have the deep bass it use to have so i return the gain to normal. Im so fustrated right now becuase I dont know whats the problem. Also, I drive a 2007 honda civic sedan and when i play my songs for an hour, is it normal for my mono amp to feel kind of hot or warm. I placed the amp in my trunk on top of the subwoofer box. Is that a good location? I dont want to bring it to a shop becuase i dont have the money to do so =(. I NEED HELP ASAP PLS!!!!

Well Tommy, I did make a video reply for you.  Real quick tip 1st: it is normal for amps to feel warm after long periods of playing, but mono amps shouldn’t ever get scald your skin hot. If they do, your sub may be bad or going bad and giving the amp too low off a resistance, causing it to overheat. Also a bad ground can cause overheating too. I hope this video answer helps, if not let me know!