Having trouble justifying the cost of rebuilding the gearbox for my Simplicity Landlord 3410 (755-01024). One gear alone is near $100. The mowing deck of this tractor is getting real tired, so I'm hesitant to invest to much into this 1972 Simplicity tractor; however, it runs fine and I recognize theirs still real value in the machine. Any thoughts or recommendations would be helpful. Thanks.