The meter change is normal because you changed the meter tubes. There is an adjustment to rezero the meter after changing the tubes. When you say the transmit is low and so is the modulation, do you mean the carrier power is lower too? If so, by how much? This will help us to identify a common problem that could affect both the RF and AF sections. For example, if the problem is both RF and AF, I wouldn't even bother to consider AMC issues yet and would be looking at any resistors that feed B+ to both stages. The Tram likes to kill many of those 2 watt carbon resistors feeding the plate voltage to the tubes. You may want to swap the relay out too because there could be an issue with the transmit B+ being switched through a bad contact on the relay.i swapped out one tube at a time starting with v600 then to v700s then to three, four, and five hundred. When i swapped out v602 and turned it on the meter on the tram went all the way to the right side. I went on swapping out and checking then when i swapped out v401, the meter went back to zero. other than that not much improvement.