How much it to replacing including any possible upgrades. 

The last electrician who came to give an estimate regarding electrical upgrading for installing washers and dryers (another post) said that it was urgent that we replace the fuses and main breaker which, he said, had evidence of "chuckling" or something like that...meaning some green colored corrosion.  

And another big factor is what repairs/upgrades/remodel the property would need to be rentable at market rates and how much will that cost?

Eventually I want to upgrade and BRRRR out an 8+ unit later on, but my cash flow isn't where I want it to be quite yet.

Is it worth starting to sell these properties and upgrading on new properties even though I probably will not be able to get the cash flow that I am getting now since most of them are already paid off. 

The smoke came out of the back window onto the back wall of the apartment complex, so the whole back wall that covers another two adjacent apartment must be painted.They said something about code upgrade that requires to replace the circuit panels of three apartments and that job alone is $40,000.

@Julie HillWhat zip code are you putting this type upgrade in counter costs?

There are tons of 3 family’s possibly move in ready or at least upgraded in your price range but in Newark/East Orange if that.

Were those properties more "turnkey" and highly upgraded compared to the first property and also the property you're about to close on?

Lots of upgrades!