The machine has no emotion and no clue 

I have been threatened multiple times by someone that does not like the agreement he made to sell me a property (sellers remorse but it occurred 2 years after I acquired the property - or at least that is when he first communicated it to me (I told him I did not have a Time Machine). 

That being said, if it is an older property that cash flow can all be washed away quickly with continual maintenance and repairs.

when she moves out, would it be best to, ask her to replace them with another pair of used machines that work or just take the loss.

I'm not in a position to just let half my portfolio not pay rent for a month or two, I would be washed out.

It's a machine to dig up opportunities, similar to a freight train.

The market you sell in is the market you buy in, unless you have a time machine.

I have a section 8 tenant who is complaining their laundry machine is making a loud noise.

Your software will be instrumental in running your rentals like a well oiled business machine. 

So its a wash for income tax purposes.