Yes, this is probably the cause.

There should not be any fuel seepage...ever.
If fuel can get out, air can get in.

Can you post a photo of the "round things"?
I'm not exactly sure what it is you are describing.
Perhaps, you mean the fuel injectors??

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022