The manual controller wheel on my Z7 has suddenly quit working...right in the middle of a major project!!! arghhh.

Can someone advise me on the best way to handle the repair service through Sony? Or any other suggestions?

Here is the site to request repair service. https://servicesplus.us.sony.biz/Sony-repair.aspx

"Depot Service" is their nomenclature for using service centers, differentiated from their on-site "field" service.

Best of Luck