[MrFixr55]

Hi RedRobot,

Congrats on your progress!!

Sorry, I should have suggested using another radio to compare reception.  You could try to install an external antenna.  There is a 3 pin jack on the back of the set.  You can connect a ground to screw #3 on the antenna terminal and try connecting a "Long Wire" antenna to either of the 2 end holes of the jack.  One of these holes connecs to Screw #4 of the antenna terminal strip.  The other connects to the secondary of the antenna transformer.  You can leave the internal antenna connected or disconnect, whether gives better reception.

+1 on the Aux input.  Either break the connection between Cap #46 and the "end" of the Volume control, or (I think the netter spot), break the connection at the other end of Cap #46, (the junction between Cap #46, Resistor #47 and the Detector output of the IF transformer #42), connect cap #46 to the common terminal of a SPDT Single Pole Double Throw) switch, Resistor #47 and the detector output lead of the 2nd IF transformer #42 to one terminal, and the Aux terminal to the other terminal.  See the drawing below:
   

In the above drawing, the "common" of the switch connects to point labeled "1" in red. This is the 0.01 uF cap # 46. One "leg" of the switch connects to point "2" indicated in red on the drawing, the junction of Resistor # 47 and the lead coming out of the IF transformer that carries the output of the detector. The other "leg" of the switch connects to the Aux Jack.. the other connection of the aux jack is connected to chassis ground.

There can be some blead-through of the radio signal when the aux input is used.  To deal with this, either tune the radio to a quiet spot or use a DPDT (Double Pole Double Throw) switch where the output of the detector is shorted to ground when the switch is in the Aux position.

If your AM transmitter can be picked up below 900KHz and the dial of the radio indicates the frequency of the AM transmitter correctly, then the radio is likely mostly functional.  There is a motherload of interference to the AM broadcast band from power line noise, CFL and LED lighting, computers, switching power supplies, automatic meter reading, the Internet of Things, etc., etc., etc.  This set is supposed to have an internal antenna.  If it is rotatable, rotate it to see if the signal is strengthened or noise is reduced.  Make sure that you replaced the EMI Caps #85 with the correct safety caps.  The hobby community refers to these caps as "Death Caps", as they often short, making the chassis hot, causing a shock or electrocution hazard.

Also check the continuity of the antenna leads, the antenna coil and clean the band switch.

You SHOULD be able to receive shortwave radio.  However, such popular shortwave stations such as BBC, Vatican Radio, etc. have shut down their transmission to North America and moved to the internet.  I don't know if 80, 40 and 20 meter HAM bands are still popular as opposed to 2 Meter (outside the range of this radio).  There are a lot of religious and talk radio stations on shortwave right now, so you should find something.  I believe that the WWV (US) and CHU (Canada) frequency and time stations should still be functional