Ltdoc's advice is spot-on. Terminating the coax from the antenna into a dummy load should clear up if the problem is the antenna or the feedline in one shot should the swr look flat into a termination.
That also looks like a double shielded, teflon cable from the photos. Hardly the type of cable I'd expect to find at a truck stop and more like 142 b/u. Maybe that's just an artifact of the photo. If it really is a high grade, double shielded cable they managed to buy some surplus runs of, there might be the problem.
Nothing wrong with it at 27 meg as it's 50 ohms and way overkill for transmission line and more appropriate for test fixtures and intercabling of test equiment or coaxial devices. The stuff is pretty stiff though and not cable that takes too well to much twisting or bending around. You may have put it together beautifully, but something may have broken away. It's such a pain to work with soldered connectors, all my bench jumpers are crimped. I don't see any ty-wraps or tape tethering the cable, so that may be a possibility since the install.
If everything is 50 ohms or pretty close to it as it sould be, the coax length despite the continuing myths, shouldn't matter. Another misconception that should be in a sticky along with power mic and limiter myths.
That ground is a good addition both for the antenna and lightening. I can't tell if the ground collar of the antenna is bonded to your garage/shack's metal structure giving it an even more excellent ground plane despite the antenna not needing one. It really helps the pattern and keeps rf from flowing down the cable.
Looks like you've done everything right. Beg. borrow, buy, or better yet build a little 5W dummy load. RS used to sell a little one for a few bucks that could take a few minutes worth of power and a larger one for about $15 with fins that could take it all day long. Something that needs to be part of your permanent kit anyways.
There might be a remote possiblitlity of a problem with the meter if you've had a long while or several drops now that most everything is plastic cased, but a dummy load on back output should clear that and the radio. If you get a high swr at the back of the meter and everything looks good and ground and center continuity check on the directional coupler, check inside the radio. If somebody has been in the radio, you may have an open shield.
I've seen some questionable soldering jobs inside radios too after a repair to the PA. Check the shield of the coax inside the radio. Some use plug type connectors often on that small, gray rg-174 type cable they use inside to connect the pa module or to the board. Those can sometimes get pulled loose or need a turn or two to get good continuity after many years. Seem a lot of that too especially in marine gear.
Do continuity checks as LtDoc suggested. That and a dummy load is your best friend exorcising these little bugs.
Hope your little one has fun. I couldn't never get either of mine near a radio until cell phones came along when they were in their late teens. Now they're glued to them.
