There is one thing you can check......but if it turns out to be the reason for your woes........you may not want to, or be able to, affect the repairs to the tractor.
To check this you will need to be able to raise the tractor frame up in front, but leave the front axle hanging.
Or, you can jack up the tractor by lifting under the front axle, then you need to figure out a way to suspend the frame of the tractor while you lower the jack under the front axle.

If you have a sturdy a-frame structure (think large saw horse or a child's swing set), you can check to see if the front axle is worn out or is breaking up and collapsing in the center pivot bushing area. Once you have the frame supported safely, lower the jack under the axle and watch to see how much the axle assembly drops in respect to the frame of the tractor. Normal, tight fitting front axle will only drop maybe 1/8" or less. If you observe the kind of wear/damage I am expecting (from your description) I expect you will see the axle drop at least 1".
This has happened to quite a number of MTD machines over the years. Some folks who can weld have had themselves a grand ole time cutting out the damage and restoring the frame and axle to accept new bushings.
Definitely not your average weekend homeowner DIY project.

thank you very much; that would explain everything.