New power service

Aluminum oxidizes and the mechanical connections degrade with time.  They make special grease to isolate it from air and this is generally successful.  It sounds like one of your connections wasn't adequately greased and developed a poor connection that heated up.  Poor connections are like resistors that heat up.  Thermography is done in industrial applications looking for poor connections.  

The good news is that that your issue never burned down your house.  Others haven't always been so lucky.  

Jerry

Did you have a whole house surge protector put in?  You really should.  Protects everything you can't put a high quality strip on, like your GFCI outlets, smart devices, refrigerator, AC, etc.

Also improves performance of high quality strips you use at your PC or stereo. 

Highly recommended.

@jea48 no it is underground  from the back alley. I had the line hydro vaced  so the cuty did not have to splice the line to the new service the line goes into the garage  and main panel there and the house is a sub pannel now instead of the other way around. I didn't  like that idea but from a practical  standpoint  that was the only way. I read one time that dan de agustino paid the utility  company  to change the wire to copper all the way back to the transformer that fed his house. It was a few blocks and cost a small fortune  at the time. He went on to say how much better his  system  was. Lol thirty years later i thought i would make sure i had  copper feeding the house. Lol i dont have that kind of cash to go all the eay to the transformer but copper from the city's  junkson box to the meter and from the meter to my house. 

@carlsbad yes that is likely  the burns look old the service  to the house was redone 20 years ago and likely  that is when it happened. I was luck because  the house is in an area where they upgraded the wiring  so I can put in the two hundred amp  service.  At one point if electric  cars really end  up coming about I got the service upgrade for free except my end after the meter. That will not stay that way if everybody  wants that. 

Very nice, enjoy!