Look at major components like the roof, foundation, HVAC, electrical, plumbing, water heater, water and sewer connections, etc. 

You want more doors, less roofs, less heating systems (ex. 1 sixteen family is better than 4 four family).Although I'm familiar with Bridgeport, I've never owned property there.

Does the roof have 5 years of life left to it?

It does have a newer roof and siding, 2 bedrooms, basement, kitchen, and 1 and half baths.

We were able to get them to pay for a new roof and sewer line before closing, out of their equity.

A/C unit inspections, Roofs being installed over old ones.

Their old apartment had reoccurring water leaker coming from the roof.

I'm no professional appraiser, but these are all 3 bed/2 bath homes built in the same era (1920s) with incredibly similar square footage and lots (1600ft/.33 acres) and same basic amenities (none of us have garages but we all have recently renovated kitchen/bath) Besides the 'hot market' that is happening in our little town, we did also do improvements to the home since purchasing it- including a new roof, gutters, encapsulated crawlspace and landscaping. 

Some items to check include: electrical, gas plumbing, heating and air conditioning, floor, roof and anything to make the mobile home habitable and functional.Once the home is ready to move in, then you can start to market the mobile home.

Maybe you have a leak, or why are the tenants using so much?