@Larry P. is right, there is a big risk when credit is not good.A good co-signer should be able to show very good credit and excess income that could be used to pay the rent should things not go well. 

I bought her a damprid to get rid of excess moisture and told her she should have opened her windows to ventilate and that she should have told me right when she noticed, but she waited several days until she finally paid her rent, after it was past due.

As long as you care about them being long term investments that are having positive cash flow I would hold on and pay down existing debt with any excessive cash.Good luck to you!

This is clearly in excess of the VA ceiling, so a second loan will be necessary.

The tenant agreed to pay a reduced amount of rent in lieu of getting part of his excess security deposit back.

Before going scorched earth on them try working out a solution, especially if they are good paying tenants.Do you have anything in your lease about excessive noise?

I do normally factor in about 20% of rent right off the top for vacancy + repairs + capex, I guess my question was more at what point should I stop saving excess income for future repairs and capex costs, and start putting it into more properties or investments?

I don't know that much about lease-purchase mortgages, but my understanding is that they are typically written for an option period of three years or less, giving the buyer time to get his finances in order and purchase the home outright at the end of the option period. 20 years seems very excessive to me.

Helmut:I assure you, I do not use the so called 1%, 2%, etc rules of thumb when analyzing a property ... nor do I put excessive credence in GRM, CAP, CoC or any of the single point-in-time ratios in isolation.  

Please also verify the accuracy of this information at the time you are considering these options as guidelines change.price Decorating allowancesRepair allowancesMoving costsNote—a dollar for dollar sales price reduction is also required for - Excess rent credit and gift funds not meeting FHA requirements Contributions exceeding the actual cost of prepaid expenses, discount points and other financing concessions Credit Requirements Required is 600.