The preamp uses all 12AX7s, but the power amp uses a 12AX7 and a 12AU7. Do you have the correct tubes in it? The 12AU7 is in my view the highest failure rate part in the amp.
You say the top side of the output looks distorted. How does it look driving NO load?
When you get the schematic, look at the two small supplies above and below the output main rails. Q3, Q4.