Develop Service and Repair manual for existing electronic products - repost

I am an independent business which has performed service and repair on NuTone brand electronic Intercom Systems for the past 30 years. There are two models made between 1994 and 2006 which NuTone never produced or published any Service Manuals for. These two models share an underlying design. The only technical information that is available for these models are some basic schematic drawings. The original engineer who designed these models no longer works for NuTone and is not interested in developing any service related information about these designs. I am looking for an independent electrical engineer to aid my company with the following tasks: 1. Provide a basic description of how these models are designed and operate, based on the limited technical information available. The description needs to be written in language that can be understood by someone with electronics experience but is not an engineer. 2. Provide a troubleshooting guide for common problems that occur with each model. This does not need to be a step-by-step guide, it does need to point to the likely cause for the failure that has occurred. Finally, the person who has performed the tasks listed above will need to be available by phone and email to discuss and answer specific questions about these two models. This support will need to be on an as needed basis while I develop the repair procedures for these models. The frequency of these support requests will likely diminish as I become proficient at repairing these models. If you are interested in this type of project, please contact me. Thank You Chris Peters