First load was fine.

Second load, lights on panel are normal, circuit breaker is fine, press start button and hear a "click" in direction of motor.

Turned drum while door switch engaged- just to see if motor was stuck. Turns fine.

Is it the motor?
- Or where to start. Nothing inside looks noticeably burned ...

Thanks

Here are your parts
Parts for Maytag MEDX600XW0 Dryer - AppliancePartsPros.com

Here is the tech sheet. It was too large to upload to this site so I had to use a third party site.
Unclick the use our download manager and then use the gray button to download the manual. Otherwise the site may put software onto your computer that you do not want.

Download MEDX600.pdf

Most likely causes are a blown thermal fuse or the belt is broken.
Since you have to open the unit up you may as well give it an overhaul.
Check the belt, rear drum support rollers, front drum glides, idler wheel, internal seals, etc.
Give the interior a good cleaning including the blower wheel.
Also a good time to clean/check your vent system. A dirty vent is the most common cause of the thermal fuse blowing.

I will go buy an ohm meter to check the thermal fuse.
Sounds like that is the likely problem.

But since the vent was completely clear, Is it likely that these sometimes just go bad - or is something else causing it?

Thanks

I would check the thermistor (on the blower) resistance.
Check/clean the blower wheel.
Check the heater. Unplug both wires at the heater and then measure across the heater, should be around 10 ohms. then check from each side of the heater to the case both should be infinite ohms. If not the heater is grounded and should be replaced.
All the above are done with the unit unplugged.

Once you get it running check the louvers on your outside vent to make sure they are opening.

There is a possibility that it is a control board issue so you may want to try running the diagnostics to see if anything pops up.
Even if it runs through them OK it does not mean that the board is OK.
There is not really a good way to check it as the fault could be intermittent but you could check the exhaust temperatures.
The tech sheet show what the temperatures should be for different settings.