Newer water heater and electrical panel. I

Use to be most municipalities would allow you to simply replace a fuse box with a circuit breaker panel I do not know about all municipalities because codes and requirements differ according to the Authority having jurisdiction in the area but here where I live if you update the panel meaning installing a new circuit breaker system you also have to update the entire electrical system , meaning rewire the entire house. 

I noticed a window or two with broken panes on the second floor, It was a two story.

. - We came into the business with enough capital that losing money on our deals wouldn't put a strain on our financials or our relationship

That doesn't mean, they are plugged in all the time, as that is a strain on cash.

Here it is:DuplexNewly renovatedNew double pane windows, siding,new furnaces, new flooring, paint, lighting, a privacy fenced back yard and a 2+ car garage and shedPrice: $59,000Yearly taxes: $1,386.36Estimated property insurance: $100 monthlyProperty management fee: 8% of rent collectedEstimated rent: $600 per doorFinance $55k @ 6% for 30 years = $330/month mortgageWhat am I missing?

If demand follows, as it once did, it could perhaps be bad for older less tech homes.Using my window analogy, in many markets you can still see single pane windows on 1970 and 1980 built homes.

All it does is raise the HOA & put more of an already financial strain homeowners thru higher HOA's.Then you gotta deal with liability. 1 builiding in our condo burned down due to an owner having a candle on the bed that caught on fire.

I planned and negotiated in sales price to replace all the windows with new  dual pane.  

{single glaze windows or bad thermo-panes}Is there a gap between the snow and the side of the building {poor insulation levels in the basement and/or above ground walls, a draughty sill plate, etc}As you roll towards spring {rumour is - it is on its way}, you can also look for movement in the foundation, stairs, decks, etc.I will case a building months (or years) before ever making an offer to get to know it.