Who noted that we simply have a porous basement wall, like every other basement wall from that time period.

You would need to let them know you are 2nd lender and want to pay the loan off.

Whether it's a legal demand for compliance or simply an email, it doesn't really matter; just make sure everything is in writing. 

The perceived value may be more, because you know an STR was run there and making money, but a lender wont value it more.While I agree a lender probably won’t value it more, an investor interested in running it as a STR will pay more.  

This is what blows my mind about the cults of seller finance - they teach you to pay anything for a home because you can put little money into it.

NeighbothoodScout shows appreciation for this century at 3.64% or ~$10.5k/year plus there will be equity pay down of -$2.7k. ~$13200  (forecast equity increase) -$4200 (cash flow) = $9k First year profit ideally that will increase annually.  

Get on a budget, build your emergency fund, pay off all debts, save up.

If I pay down $50K, how can I calculate the new monthly payment?

No fees, no pre-pay.

@Matthew Cook I would NOT pay for the renovations unless I was on title or had a very formal contract written about the split of profits.