2010 Husqvarna Huskylock S21 / S25 Sewing Machine Service Manual & Parts Lists (P/N 104 73 00-26)

This VSM Group service publication (104 73 00–26, dated June 3, 2010) covers mechanical adjustments for the Husqvarna Huskylock S21 and S25, plus electronic service functions for the S25. The set also includes a separate illustrated parts list for each model.

Text search and diagram detail: All three PDFs contain searchable text but no embedded bookmarks. Small connector labels and the dense display troubleshooting chart are readable when enlarged.

• Needle and looper settings: Needle bar height and parallelism, needle timing, upper and lower looper synchronization, chain stitch looper movement, and needle guard clearances.

• Feed and cutting mechanisms: Feed timing, feed dog height, S21 differential feed adjustment, upper knife timing, lower knife alignment, and seam width settings.

• Thread tension and guides: Separate S21 and S25 thread tension unit adjustments, plus looper thread guides and chain stitch thread take-up settings.

• S25 electronic diagnostics: Service modes for touchscreen calibration, display testing, thread tension adjustment, function-button checks, sensor checks, and foot-control input testing.

• Electrical reference: Main PC Board and Power PC Board connector diagrams, plus the display/screen troubleshooting chart for tracing electronic faults.

• Parts identification: Exploded views and part tables for the needle bar drive, presser foot linkage, lower looper shaft, upper knife assembly, and main drive motor.

These instructions are intended for service workshop personnel with thorough knowledge of precision equipment and access to the required service tools.

Mechanical Adjustment Parameters

The cover-removal section identifies the panels and the S25 front-cover cable connections. The setting chapters pair checks with adjustments and follow-up checks.

The Basic Position of Eccentrics drawing supports reassembly after lower-shaft work. Those positions are approximate; the individual setting sections provide the final alignment criteria.

Repair setup: The tool list identifies needle clamp 413 10 22-01 and setting gauge 416 38 44-01. It also specifies the ELx705 size 90 needle used as a reference for setting work.

S21 Tension and S25 Service Diagnostics

The S21 tension section uses mechanical dial settings. S25 coverage distinguishes basic thread tension setup from fine adjustment through the service program and explains the prerequisite checks.

S25 sensor tests cover the front door, presser-foot lift, arm-shaft synchronizer, and foot control. The display/screen troubleshooting chart separates button faults, touchscreen calibration problems, and front-cover distortion, helping a technician narrow down the cause before choosing a repair.

Circuit Boards and Parts Selection

The board layouts identify connectors for the display, thread-tension motors, feed and stitch-length stepper motors, and power supply. The circuit-board section warns that electrostatic discharge can damage the electronics and specifies power disconnection and ESD protection for board removal.

Model differences: The separate catalogs distinguish S21 mechanical tension controls from S25 stepping motors, LCD, and circuit boards. Motor, power-supply, and foot-control entries identify different voltage or market versions, helping match replacement parts to the machine during a repair.

Motor and timing-belt components are covered in the parts lists; dedicated motor-replacement and belt-synchronization procedures are outside the service manual's scope.

PDF Set and Included Pages

The ZIP contains three printable English-language PDFs totaling 118 pages: the 44-page service manual, 37-page S21 parts list, and 37-page S25 parts list. These totals include all three covers and six other introductory pages, including the service manual's contents page and the largely blank second page in each parts list.