son has tried filing fed return for 3 years with turbo tax verification code turbo supplies is shorter than fed expects. he constantly has to mail

Sounds like your son is confusing a "verification code" for e-filing with his AGI.   The IRS wants the prior year AGI in order to verify that the person using that same SSN is filing the tax return.  His AGI is on line 11 of his 2022 tax return.

Or-----did he request a six -digit IP PIN from The IRS?

If you have a 6 digit PIN issued to you by the IRS you need to enter it in order to e-file.  Go to Federal>Other Tax Situations>Other Return Info>Identity Protection PIN and enter the six-digit PIN.