Set multi meter to Amps scale & fit in series with the positive lead going to the battery from the solar regulator. It should show some sort of current going into the battery.
Yes its hard wired as the leads are too light to carry 10A (This meter is not to be used on mains voltage as there would be a risk of shock) It was a $5 multimeter from Cheap as chips, i bought 4 of them at the time & acuracy is comarable to my expensive multimeter.
I see the anologue voltmeter has been rescaled too. I used to do that when building test equipment too. We used to get stacks of old meter movements and when we needed one to fit to a project, just replace the shunt resistor with a different sized one then cal it and print up a new face card.
Got the analogue meter from a scrap yard for free. It was a 250Amp meter from a telephone exchange battery charger. Amazing whats thrown out these days.