adcom pre amp

sophie

my adcom gtp-400 preamp is having issues with the phono stage working right. the right channel cuts in and out sometimes and sometimes is half on half static. if i stomp on the ground it will go back to working for a while(up to 5 min.) then cut out again.i have opened it up and checked the rca to the solder point on the board and it appears to be a good connection. is this something i can trouble shoot myself or should i send it in for repair? other option is to sell to someone who doesn't need the phono stage or tuner (never worked).

any help is great,
Payton