The remaining interior wood is still vulnerable.  

It is also possible to start off with a regular Forward 1031 Exchange, sell and close on as many of your relinquished properties as possible, and then combine/merge the Forward 1031 Exchange into a Reverse 1031 Exchange, which would allow you to close on the replacement property with those relinquished properties that have already closed and then go into the Reverse 1031 Exchange, which would provide you with another exchange cycle/period to complete the sale of the remaining relinquished properties.  

In my opinion I have three options and hoping you pros have some great ideas:1) Hiring a professional commercial boiler expert to thoroughly clean the boiler and go through the whole system with a fine tooth comb.2) Do the HVAC conversion in the soon to be 4 empty units and keep the boiler working for the remaining occupied 3 units. 3) Do the HVAC conversion in each unit one at a time and when I get to the units that are occupied I'd offer them the other units to sleep in or perhaps rent them a temporary place to live. 

Then, it will generate a little bit of return each year [ie. 5.5%/y, MINUS any remaining mortgage you're still paying off].Let's look at it from a cash investors point of view: They have $230k to invest.

I assume the shower doors slide in a track.. if so,  to remove the doors is rather easy you lift off the top track and lift out the doors,, the side rails and bottom track would remain, so you could put the shower doors back in.

There's likely some kind of environmental escrow and you can see what the cost of the remaining work is to assess your potential liability. 

She will of course remain a challenge going forward and ultimately you will want to get rid of her.

When purchasing a property that is occupied the lease transfers with the title, therefore you are required to honor the remaining duration of the lease. 

And it is a rare, very rare occasion where I have lowered rent even in a recession, so even if the value has declined and the rent has remained the same; I'm more likely to keep that property rather than sell. 

@Nicky Garza basically from the 13k, 11k went into the actual loan and the remaining for additional closing costs (roughly speaking)I did, I used an online service for credit and background check.