Swap the tubes in the main section. not the phono sections. just the mains, 12AX7 and a 12AT7. 50-100, bucks then you'll know it's not a valve at least. You can use one from the phono section, but there are no other 12AT7s to swap with.. Need to have one on hand, borrow, buy.
My C2500, had a slow turn on, on the right side 20 sec or so, and had a slightly lower volume. Not balanced, took longer for one side to warm up and pass boot up, then pop. Came on.. Valve swap and no more problems... They were factory valves (made in china). Amprex, did wonders. Solvex/ RCAs and Silvanias did a good jobs and better than the stockers...
Regards
My C2500, had a slow turn on, on the right side 20 sec or so, and had a slightly lower volume. Not balanced, took longer for one side to warm up and pass boot up, then pop. Came on.. Valve swap and no more problems... They were factory valves (made in china). Amprex, did wonders. Solvex/ RCAs and Silvanias did a good jobs and better than the stockers...
Regards