No worries, glad it worked out.

If your mates amp reads 7.6VAC and the heaters read 6.93VDC then it maybe a different model/revision.
There are several ways to rectify AC into DC and they all have different outcomes.
It may only have a halfwave rectifier which would yeild; .9 times the AC.
So 7.6VAC x .9 = 6.84VDC.
A much better outcome for the heater voltage and half wave Only requires one Diode,,, but Full wave gives better noise results.
It's debateable if you would notice the difference in buzz or hum.
http://www.hammondmfg.com/pdf/5c007.pdfNote the maths below each type of rectifier setup.
Re heater current draw.
EL84 draws 760mA
AX7 about300mA
There will always be deviations due to manufacturing processes. So don't expext perfect results.
And don't forget the meter you use may not give the exact same readings as another DMM.
Oh and be careful reading mains voltage with cheap DMM's as some are not really up to the task.
Re mains voltage fluctuations;
I think **Enzo** has already made comment on that?
It fluctuates all the time and the amount depends on where you live,, how far from the power station,, how close is the booster transformer,, are you at the end of a long line,, and so forth.
Re zip ties;
They are plastic and will melt or at least stretch if that 5 Watt resistor gets hot.
Which is why I mentioned block connectors as you can screw them down.
You use a double on each end and that gives you one mounting hole on each end of the resistor. This gives the resistor a solid mount at each end.
The noise problem explained,,
And why DC heater still won't fully fix bad hum:
I quote from this page
(
http://web.archive.org/web/20071024154401/http://users.telenet.be/svokke/valve%20junior%20mods.htm)
--------
"The layout problem is mainly in two places. At number one there is Crosstalk between the heater and the trace from the volume pot wiper to V1B. At number two there crosstalk between heater line and the trace between anode of first gain stage to anode load resistor (R3). I can't believe that they didn't discover this at epiphone. After all, they should be the pro's. There is also some crosstalk between heater and the trace between anode of second gain stage to anode load resistor. On this location it is less important though because the gain following this stage is low."
--------
Same old problem as my mates Fender Pro Junior.
Cross talk between tracks.
Obviously people in front of a cad program who have no idea what happens when you put high voltage tracks right next to noise sensitive hiZ tracks.
they hit the auto route and go to the pub,,meantime the consumer has to put up with
The HUUUUUUUUUUUUUUUUUUUUUM.

This particular model of Pro Junior was a shocker and I fixed that by cutting tracks and running shielded cable direct to valve pins.
hum gone with no DC heater needed

Phil.