Sputtering / Coughing Sound From HRDx

[Padrino]

So my heavily modified Fender Hot Rod Deluxe (Fromel Supreme Mod Kit ) with a Eminence Cannabis Rex Speaker in it started making this "sputtering" and "coughing" sound whenever i play. It will continue after i stop playing for a little while. On top of this, whenever i plug my board into the effects loop, it gives mad howling feedback. I checked all my cables in the board, and plugged the board into my SS practice amp, and everything behaves just fine. But even with the guitar plugged direct into the amp, it still does coughs and sputters out.

 

This is a brand new amp, bought in December, swapped the speaker in Feburary, modified in mid June. The amp worked perfectly for the week and a half i had it in my apartment, and just started acting up tonight after i moved it.

 

I've got a couple ideas of what it could be, but if anyone has any other thoughts, i would greatly appreciate it. I'm taking it into a tech tomorrow to see if they can catch something i may have overlooked, but would like to have a couple suggestions/ideas to give him.

 

I'm thinking its either:

-Some sort of bad tube (probably preamp since the effects loop feeds back like crazy)

-the speaker polarity is revered (not sure how thats actually possible...but it popped in my head)

-some sort of loose/rattling input jack?

 

Any thoughts?