help? porta02 mkII output volume problem...

[semiperilous]

hi, my porta02 has low output sometimes. goes in and out for unknown reasons. a loose connection?? i dunno

when it goes into this "low output mode" i have to crank the master volume to hear through headphones and also when sending it through the rca outputs to my CD burner it sends it at low level. it used to come and go and now its just staying at low output level. i've recorded on this low output mode and later when it goes back to normal the level of the recording is fine.

can anyone help?? any tip would be greatly appreciated!!