I don't think it matters whether you put it on line 1a or on line 1b, the result seems to be the same.
For your question about where the excess is, it might depend on how your custodian logged the contribution. I mentioned earlier that when making my own contributions to an individual 401(k) (not from being a notary public) that the form on which contributions are submitted requires that I designate the amount that is elective deferral and the amount that is employer contribution. That form is used by the custodian even for contributions to 401(k) plans that are not individual plans, so perhaps that breakdown is just for informational purposes. I don't know that the IRS is informed of the breakdown, only the total self-employed retirement contribution that you show on Schedule 1 line 28, so it seems that you *could* consider your elective deferrals to be $24,500 and the entire excess of
$24,500 + $7,500 - $26,264 = $5,376
to be in the employer contribution, with the remaining $2,124 of employer contribution being under the $4,062 maximum permitted.