When you sell machinery that is fully depreciated, it is all taxable. Machinery values have
plummeted this year, consider that in your decision.  Also consider your health, think about
getting ready for a sale it is a lot of work, so do it when you are able, maybe you have hired help,
that would help a lot.  Sometimes having a C. Corp. can complicate things when it comes to
this period of your life.   A sole proprietor can set up a defined benefit pension plan to defer
machinery sales income into a retirement plan.  A very efficient tool that is a nice advantage.
Good luck with your plans, it is complicated.