Small Engines (Lawn Mowers, etc.): Craftsman mower with Tecumseh rope wont pull, compression stroke, point ignition

Question
model 917.376950 Craftsman mower, serial 012496M000516, Tecumseh engine model 143966506, serial number on housing, STP207UIGIRA, engine family DOM6019K   
BEN,
I have a Craftsman mower model #917.376950 which suddenly became impossible to start.  The rope pull won't pull at all.
The breather element is working.  
I tried taking the oil cap off but that didn't help.
When I take out the spark plug, the rope pulls easily.

The electric starter works but is only spins the engine a bit and then hits the resistance and at the compression stroke it stops, and will  not start the engine.
I checked the valve clearances.  It is about .0055 inch.
I took apart and checked the compressor release and it looks ok.
When the timing marks are lined up, the piston is up Top Dead Center.
This is making me wonder........is it possible the timing gear could have slipped into the wrong position on the crankshaft?  
When you pull the rope, you get a lot of compression.  First it drops off a little and then there's a harder resistance.
After you get to the top of the compression, it adds a vacuum resistance and is impossible to pull at all.   Any ideas of what else I could try?  
Thank you very much for any help on this,   Will

Answer
Will
I would say it probably is out of timing,you may have to recheck the flywheel to make sure it is not 180 degrees out.
Just for your information this # 143966506 is not a Tecumseh engine # they usually will start like this.

4-stroke L-head    STANDARD POINT IGNITION    VM80, TVM195, HM80, HHM80     
4-stroke L-head    STANDARD POINT IGNITION    VM100, HM100    
4-stroke L-head    STANDARD POINT IGNITION    TVM220, HM100     
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS75 ( 8 / 87 & earlier )    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS90   
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    H35   
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    V40, TVS105, HS40    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS100, ECV100, TNT100    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS/ TVXL115 57000 Series Only    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    LEV115, TVS105 56000 Series    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS/TVXL 115, 57000 A & later    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    TVS120 J & later   
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    HS50 H & later    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    HSSK N & later    
4-stroke L-head    SOLID STATE AND EXTERNAL IGNITION    LAV50, TVS120