Money, this has two sides, first is the contribution to share the benefits, secondly, is the partner strong enough to suffer a loss, can they inject more if required, can the back up guarantees with thier check.2.

Rodents love plants that are against the house.

put up a few sections of lattice on your side of the shed with vines planted on them.

Learned a few things and happy I asked the question.I'm going to 'eat' that cost and try to get a few brownie points by calling the tenant and let them know I covered it this time due to them being good tenants, but plant the seed/set expectation future maintenance/repair for supplied appliances are to be handled by the them per the lease agreement.Hopefully can finesse that message so as not to lose more goodwill than earn brownie points!

However, like many people out there, I think I'm suffering from that old problem of "analysis paralysis."

Either way it may be cheaper to suffer whatever loss breaking the contract costs rather than continue to have that many units unrented.

If you knowingly rent to a violent felon or sex offender and the neighbor's suffer, you may be on the hook.  

We suffered too, and we are not newbies. 

A few welcome gift ideas: A plant with nice note, new welcome mat, printed address labels or custom stamp, gift card to nearby movie theater or restaurant, bottle of wine... 

The house could use some curb appeal with some flowers/plants.