missing deferrals, no termination documentation, merged into PEO plan

[DMcGovern]

Small 401(k) plan intended to terminate plan and merge assets into a PEO plan a couple years ago.  Client never paid for final reporting (including 5500), or termination documents and did not respond to requests for information/payment.

Two years later client receives a letter from the IRS requesting filing of the 5500 for that plan year.

We can certainly do the final reporting and have started the process.  During a review of the transactions, we discovered that one of the participants (also an owner) is missing $509 in salary deferrals for that final year. 

So, there are document issues to fix, along with the missing deferrals.  Since all of the assets are no longer in the investment accounts for the plan, not sure how to fix this.  Use a bank account in the name of the plan, then deposit the deferrals + earnings and transfer to the PEO plan?

For the document, the intent was to terminate the plan in March 2015.  With the deferral correction that is needed, would the termination date need to be current?  Not sure how to proceed on this.