Troy-Bilt Pony

Is the starter pinion gear meshed with the flywheel when not turning the key?

My question is why Ian you held it in start position until you smoked the starter or did the starter solenoid hang? Now the starter is definitely ruined.
 
As to the terms Mike was referring the starter gear (pinion gear) to flywheel ring gear. Although the starter gear is normally meshed (teeth one gear properly entering the other) properly they can hang up at times. But I doubt that would could a total seizure. One thing to watch for here is you have the correct starter gear as there are 14 tooth and 16 tooth starter gears and they are not mixable as will have ring tooth entry problems causing both a dragging starter and ring gear damage if a steel start gear is used on a plastic ring gear.
 
I do have some other questions as can you freely turn the engine by hand with the spark plug out? This tell if the engine is locked up or not.
 
Actually for remote troubleshooting I would need both the mower model number from the serial tag and the engine's model and type number. But the following might sense as it a list of possible problems.
 
Currently it could just been a starter that the permanent magnet came lose binding the rotor or seized engine. People are bad the strike these permanent magnet starter motors with a hammer knocking these magnets lose. These magnets can also come lose naturally. Most times they are trying get the starter to turn pass a hard compression stroke. But now I know you will at least need a new starter and starter solenoid in addition to what else.
 
If this is 31/330000 series engine it is a good that the engine has been ran without oil. These engines are bad about blowing the head gasket which leads to excessive oil usage. May not even smoke during this time. I have personally seen one engine to use a quart of oil to a half gallon of fuel and not smoke. Without oil the piston rod seizes to the crankshaft journal. Once this aluminum transfer starts there is no way to stop it except cleaning the crank journal and replacing the rod. Sometimes can happen during running resulting a snapped rod that can go through the side of the crankcase. Result a ruin engine.
 
There are few possible root causes as trying the start the against a hard compression stroke. There are three possible causes of hard compression.

• Valves out of adjustment effectively disabling the ACR (automatic compression release).
• Camshaft ACR broken.
• Engine's cylinder is hydro locked caused by a leaky carburetor. Usually the crankcase will also been over filed with gas diluted oil.
• These are the most common problems but are others too.

 

Haven't had a chance to look at anything yet, but I found the model number (13WN77KS011) and serial number (1E313B10416). They were under the seat. Not where I would have expected to find them, but maybe that's just me.

Yeah I would take the battery and have it tested first. Then like AVB said earlier check the valve clearances because it could be off like he said making it harder to start due to compression.

Could be, I tried three times to watch the 1st video but couldn't so watched the last two

Whenever you smoke the starter as much as you did the enamel coating on the wiring of the starter rotor would be burn off leaving shorted spots plus the brushes and commutator ring are damage. Personally I would replace the starter that is mainly because I back my work with a 30 repair warranty and I hate reworks just I use some short cut.
 
If comes to checking the cylinder head and  possibly replacing it requires removing the current head; unless, you have a very good lighted inspection camera with 90 degree to 180 degree reverse angle adapter to view the valves and seats which fit through the spark plug hole.

Any problems after installing a new battery?

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