Baloon mortgage payment
You can still refinance your entire current package at cheaper lower rates. We just refinanced from a fix 30 at 6.25% down to a fixed 30 at 4.5% to take advantage of cutting our monthly payments in half.
Your existing first mortgage and second (baloon) mortgage will be paid off by the new mortgage when you close on the new loan.
It's interesting to me to go to a website that has amortization calculators (there are several), and run some scenarios. Take a look at how much you're paying now (interest and principal) vs. some alternative loans.
Sounds like refinancing could pay off nicely for you. Why pay all that interest if you don't have to!?
Barring that, sell it and come to California where plumbers make a great living. I got a job for you now! Need to get rid of a water softener and figure out what the deal is with this pressure tank on my system (public water).