SEBO Screw C 3.9 x 19 (DIN 7981) for K Series, 370 ELECTRONIC and DUO

Between the 16 mm and 25 mm versions sits this one, the C 3.9 x 19 to DIN 7981, which SEBO specifies for the K series, the 370 ELECTRONIC and the DUO. It is sold singly under part number 105. Like the rest of the DIN 7981 family it carries a cross-recessed pan head on a self-tapping thread, cutting its own path into the moulded boss and needing no nut behind the joint.

When a screw in this size backs out, the shell it holds begins to move at the seam, and that movement then works on the fasteners either side of it until one loose screw has quietly become four. The symptom starts as a click or a creak as the machine changes direction rather than as anything dramatic. Catching it early keeps the repair down to a single part instead of a panel with four ruined bosses.

• Part number: 105
• Fits: the SEBO K series, the 370 ELECTRONIC and the DUO
• Specification: C 3.9 x 19 to DIN 7981
• Head and drive: cross-recessed pan head
• Size: 3.9 mm diameter, 19 mm long
• Sold: each
• Neighbouring lengths: part 103 at 16 mm and part 104 at 25 mm, plus part 102 at 13 mm

If the hole has opened up rather than the screw failing, the repair belongs to the housing and not to a longer fastener. Driving a 25 mm screw into a seat sized for 19 mm simply moves the damage deeper. Check the length you removed against the specification above, since the four screws in this family are identical above the thread.

Tighten to firm hand pressure and stop there. The thread this screw cuts is in plastic, not metal, and it will accept far more turning force than the boss around it can survive. The characteristic sound of that mistake is a short creak followed by a screw that suddenly turns freely, at which point the fastener is no longer the part that needs replacing.

Order this one when searching for a SEBO K series body screw, a SEBO 370 ELECTRONIC casing fastener, a DUO 3.9 x 19 replacement or a genuine SEBO 105. Genuine SEBO hardware supplied by an authorized dealer, shipping in 2-5 business days.