If yall don't have wiring schematics... the first thing I would do is tell the customer to provide them to you. A17.1 code requires them to be onsite, and its the customers equipment and, more importantly, customers responsibility to provide the wiring schematics. They may have to call schindler and exchange a large sum of dollars to get them, but its important you don't let off getting those schematics onsite. Sometimes we'll help a customer source schematics but ultimately they have to foot the bill if it cost money to get them. Explain to them that the first service call their elevator could be down for awhile if you don't have the schematics to intelligently work on the equipment, and the first annual inspection it will fail and they won't get a certificate... don't be scared to remind an inspector of a code they should be enforcing.... I find it also helps when the customer understands their previous company did them dirty and stole their paperwork from their building.

Now I'm talking about the wiring schematics. It's going to hard to get the install/service manuals or fault lists etc in the same way. But It's a small world and we all help eachother across the aisle for the most part. If your with a smaller company hopefully someone on here can help with fault lists/service manuals or try calling friends of friends in the trade to see if someone will help you out. Not uncommon around here to meet someone from another company at a gas station to swap parts or papers.