Can’t find the manual, need help with Pfaff tension issue

[Vig34]

Guys and girls, I urgently need a manual because my old faithful Pfaff has started acting up right in the middle of something important. I decided to sew curtains from heavy velvet, and suddenly the machine started skipping stitches, and the movement feels stiff, like it doesn’t have enough power to push through the fabric.

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Has anyone come across this issue with German sewing machines? Could it just be the mechanism clogged with lint from the fabric and needing a deep clean with partial disassembly? And are there any special lubrication requirements for this brand? I’m afraid to use regular sewing machine oil in case it damages internal plastic gears, if there are any inside.

[Ember_Tide]

Velvet's a real challenge for any machine 'cause of all the micro lint that can clog up the hook mechanism right away. Your skipped stitches are most likely caused by dust interfering with the timing between the needle and hook. I don't have the manual myself, but there's a good website with manuals for different models - manualmachine.com. Well, for Pfaff, it's better to use the official clear sewing machine oil - it's a light mineral oil. It doesn't get thicker with time, and it's okay for the inside parts. Have you cleaned the area under the needle plate? That's most likely where you will find a real felt-like accumulation of thread and lint, which really slows things down. Besides, a bent needle can cause the problem, even if it looks straight to you.