ML-335 or 336 Service Manual

Greetings Folks,

Am working with a family member to diagnose and repair their treasured ML-335 which an uncooperative authorized ML repair center performed repair work on and sadly still has issue which the dealer is unwilling to diagnose and repair without an additional fee. He can’t afford another multi thousand dollar fee , so I’d like to, help, but before I get in too deep into D&R I’d like to ask if anyone in the community would be able to please share the service manual or any circuit diagrams?

Thank You in advance. Phil