This service manual provides detailed information on the EF4-B511, EF4-B531, and MA4-B551 sewing machines. It includes features, installation steps, mechanism descriptions, disassembly and re‑assembly procedures, and adjustment guidelines for various components such as the differential feed and double‑chain stitch looper.
The document also contains extensive specification tables for stitch forms, needle gauges, and recommended attachments, as well as troubleshooting check‑point adjustment pages to help service technicians resolve common issues like wrong threading, tension problems, and feed dog alignment.
| Maximum presser foot rise | 7 mm |
|---|---|
| Maximum stitch width | 7 mm |
| Needle gauge (available on request) | 3 mm |
The differential feed ratio can be easily adjusted with a lever without using a tool.
Adjust the thread guide to the proper position as indicated in the check‑point adjustment page.
Adjust the presser foot pressure to the proper level as described in the adjustment checklist.