Has anyone searched for online manual for old sewing machines?

[StormBreaker]

Last week, I inherited a Husqvarna Viking 6440 sewing machine from my grandmother. It's a real workhorse from the '70s, but I ran into a problem. After sewing through thick denim, the shuttle got out of sync, and now the machine either skips stitches or breaks the thread every other stitch. I need detailed instructions on how to adjust the shuttle and synchronize the mechanism because standard modern guides don't mention this kind of mechanics. Does anyone know where the technical documentation archives for these vintage models are kept these days?

[StormBreaker]

Is it worth looking for service diagrams to lubricate the internal components, or is drip oiling "wherever you see fit" sufficient? I’m afraid that if I take the housing apart without a diagram, I won't be able to put all the levers and springs back together. Has anyone on this forum had a similar experience?

[SonicNova]

I understand that the manual for this model hasn't been available for a long time. I work in a workshop where we restore old household appliances and tools. People often bring us mechanical monsters, like old Husqvarnas. We constantly use the website https://manualmachine.com for our work. Try looking there, too. I look specifically for needle timing diagrams and lubrication charts so that I don't pour oil on parts that are supposed to stay dry. Go to the homepage and enter your model series. I'm sure you'll find a step-by-step setup guide. Have you tried searching by model number, or have you just been browsing pictures online?