Temp still looks to be a bulb and tube mechanical unit, not and electrical type.
I had not done this for years but in past had a quick "dirty" check on the amp meter using a standard cheap 9v carbon battery (disposable). New out of package these provide about 5 amps of short circuit current. You apply the 9V terminals to the amp meter terminals direct for a second or two and should read about 1/6 - 1/4 of the scale for a 35amp meter. Then flip the battery and read the other direction.
Again a second or two at most to keep overheating the battery to minimal. The battery life will be sucked out of it so get cheapest battery you can find. No rechargeable battery types as short circuit is no good for them.
If you still have a radio shack go and buy model 270-324 catalog #2700324 Heavy-Duty 9V Snap Connector. for battery a HF 9V battery item#68383
