need help troubleshooting

here is my situation.just bought a turntable,hooked it up to my pre which is a modulus 3a.i only had sound out of my left speaker but very faint.heard quite a bit of feedback out of the right speaker when i touched the tonearm and i could hear music playing out of my cd player even when the pre was set to phono.i then tried alternating tubes,switching linestage for the tubes that were in the phono positions,situation remained unchanged.both speakers run when i play cd's but now with a lot of distortion when they had previously been fine.flip flopped the phono cables but that didn't help.the tt was used but i listened to it in the store,however not with the pre-amp.any help would be appreciated.