Hi CJ,
I hope you didn't mind me suggesting getting help with fixing your bass sub, but what concerned me is that often you can create more havoc trying to repair complex equipment if you don't have all the test equipment and the service manuals. I have done just this.

My mate, who services musical gear, tears his hair out when he gets a rig that has been previously 'serviced'.
As I have said many times before, it is a great shame that you are not just down the road, because I could then call around and advise. It is extremely difficult, as many of us have found on ETO, to do remote fault finding.
But we will have a go and see what can be done. I will consider the next move.
About getting components, that is easy, especially as you are in the States and most components on a bass sub are liable to be standard types. DigiKey is one of the most popular component distributes with home makers. But, Mouser, Arrow, RS (Allied), Element 14 (Farnell) (Newark) are good too. There is also a slew of smaller distributors and then there are the budget retailers, ebay being the biggest, followed by Alibaba and then Amazon, I guess.
https://www.digikey.com/
https://www2.mouser.com/?gclid=CjwK...ZUejah5v8ygTisC9ahOSutP6GZ1q1isW4WhoCzI7w_wcB
https://www.arrow.com/
https://www.alliedelec.com/
https://www.newark.com/
As to sleep, I generally hit the hay around 12.30pm and sleep until 7am, if I have been active. But if not, it is 1pm, up at 4am, back to bed at 6am, sleep till 8:30am. But I also tend to fall asleep on the settee around 7pm for half an hour. On the other hand, after a few pints of Butcombe (excellent local real ale) it would be bed at 1am and oblivion until I get a dig in the ribs from the missus, some time the next morning.
Before I retired, sometimes we worked 24Hrs with no sleep, when there was a panic on.
spec