Picture #1 shoes 10 gauge wire feeding the sub panel. Pic 2 is 100 amp main breaker for the service panel. Pic 3 is the sub panel and the last pic is the service panel. I know there is a lot more going on here but my questions are specifically: Why are the is the main breaker for the service panel all the way at the bottom of the panel, and why are the service entrance cables not going to the main lugs instead ? Is that allowed ? Also, they had a 10 gauge wire feeding the sub panel and they were going straight into the main lugs in the service panel rather than to a breaker, shouldn’t it be going to a breaker instead? And finally is 30 amps (the rating for the 10 gauge) enough for that sub panel ??
Electrical nightmare, The gecko did not know what hit him, Is that a snakeskin? O I see that you have mud daubers too, Everyone can pick at this one. 
The main does not need to be at the top. Why do you think it does? A panel can be backfed through a breaker if a means of hold-down is installed.
The feed to the subpanel should be fed from a breaker. Whether the 30 amps is enough would take a calculation.
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There is a lot going on here, follow everything out carefully.
Those terminals are unlikely approved for #10 wire, how far was the subpanel fed by #10 conductors?
There is enough copper there to make it the right size, Simon. 
LOL!
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Good enough for this neighborhood! 
The sub panel was inches away from the service panel Simon.
Thanks for the reply Jim. I guess since there is no room left in the service panel they just ran the #10 for the sub panel straight into the main lugs.
You can use those main lugs to feed the sub-panel with smaller conductors as long as the tap rules are followed. In this instance they’re not. If the feeder conductors for the sub are the same size as the SEC’s feeding the 100 amp CB then no tap rules are required to be followed.
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I put an explanation in your other thread.
That ITE panel dates back to the mid 1960’s or earlier, which predates the requirement for a breaker hold down on back fed plug in breakers by decades, the hold down requirement first appeared in the 1990 NEC. I do agree the panel needs a lot of help, it is also a pre CTL panel which means it does not have notched bus stabs to use CTL twin breakers, but there are non CTL models available.
Why was the hold down requirement included in the NEC? Safety!
I’d report on it, no matter when it was required.
If a backfed breaker were to be removed or pop off the bus it leave live parts exposed. The hold down keeps the breaker secure, especially if someone did not dress the conductors to remove stress against the connections.
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