Lower joints will always show slack when the weight of the vehicle is lifted. They are designed to be loaded in service. The uppers are not the same and should not show any slack. If the "parts changers" check both upper and lower in the same manner, find a better place for your repairs.
"The other odd thing was the valve was gone, along with the valve extender."
Must have rubber valves instead of metal ones. More than likely the weight of the extender pulled the stem out and caused the flat in the first place.
I would imagine that you will go via the Cassiar. There is a place at Kitwanga about 50 sites I think. Not too bad and away from traffic. Phone # from 2years ago 250-849-5799 / 888-678-7275
Best luck & good health Art.
Connect trailer to TV but DO NOT connect electric. Pull breakaway pin an try to move trailer. Wheels should be locked.
Also if you have an ohmmeter check resistance for trailer brake circuit. Should be about 1.5 ohms for single axle.
Edit to correct stupid mistake on resistance A.
Brakes for 7K axles are the same as 6K * EXCEPT * for the magnets and lineing material for the shoes.
Bolts right on the 6K axle.
For the few dollars extra get the self adjusters. They do work very well
Since that Thetford link doesn't show the part. on the list it is #6. There should be an 'S' shaped piece of hose connected to make a water trap. It is actually an overflow for the bowl. Every time you flush, a small bit of water should enter to keep the trap full.
Volts don't tell the whole story. Put an ammeter somewhere in the line near the trailer hitch. You should see arounnd 3 amps per wheel ( 12 amps total for four brakes) when you activate the manual brake control.