Hi,
At first sight almost everything seems to be ok. The DC values are on track. The AC values also, apart from the output swing out of both the 6V6. I can't understand why you get such a low swing. The input at the 6V6 is for my taste a --- low but that can lay at a lower gain of the PI tube. Anyway, your problem is at the output stage. The PI seems to do his job in term of bringing a signal to the 6V6.
The difference of idle current is surely quite high but should not be an issue. Anyway, matched tubes live their own life after they are running under real conditions. Matching is mostly done at 1 single point of measurement. This does not indicate whether the other matched tubes have a very near characteristic. Anyway, this should not be the problem of your low output power.
If we assume that your tubes are both new and matched, the probability that both are nearly dead is very low - these are not sensitive transistors.
That means that this low output swing out of the tubes is limited through (maybe) an odd reflected impedance from the secondary winding of the OT to the primary of the OT, which is connected to the 6V6. As you seem to have wired the OT properly & your output jacks are wired the proper way, the OT must get checked.
You have the choice to unwire it completely or to leave it in place as is. Just remove the 6V6 in this latter case, in order to make sure that none of the wires is connected to anything.
But you should unwire the CT, in order to make sure, that you have no connection to the supply rail. Secure it and make sure you can access it for measurement.
Then:
1- Take the datasheet of the OT from the shop product page
2- Measure all DC resistances and compare them with the datasheet. Are they all in the ballpark where they should be?
3- If everything OK, we can move to the AC test. Connect the signal generator to the secondary at the 16 Ohm jack.
4- Then feed a simple 1V signal.
4- Check at the primary what you get between plate-CT-plate ? The plate-plate measurement gives you in this case the turn ratio of the transformer. For this OT at the 16 Ohm, you should get around 22V at the primary.
5- If ok, move the signal generator to the 8 & 4 Ohm taps. You should get around 32V and 45V between the plates. Also check what you get between the plates and the CT.
If everything still ok, then we could feed 5V and repeat to see, what you measure. But first make the measurements and post them, so we can see, what you get.
But if everything is fine, I have no clue, what happens...
Laurent
EDIT: having had another trouble in the past with a cold solder joint at the CT, maybe try to check this one first, even if your DC measurements seem to be ok.
