fender bxr 200 head problems,help?

[3mtlbass]

i bought a bxr stack today off cgraigslist.it sound freaking awesome however if i unplug the bass cord from the input and put it back in while the amp is on i get a loud constant noise and no bass signal.if i cut the amp off and back on its fine!***?hard to rely on it for gigs...it works but i always wonder if its gonna fire up!

[BassmanPaul]

Your amp needs to go to a tech and be checked out. May simply be a cracked solder joint that needs to be re-soldered.