When I think of something like this I will post it.
My friend who was trained in a European sewing machine factory also told me this:
1. Most sewers use far too large a needle, this is particularly true when they work with thick or dense fabric.
His rule: use the finest needle you can. He liked 60 for thinner cottons and rarely used a heavier needle at all, say a 100 (this is metric translate this to a 16).
In fact he said that the most important part of the needle was the point and that the pointier the easier it was for the needle to pierce the fabric - for wovens he recommended a "sharp" needle and didn't really like universals which he said were like rose wine- not as pleasing as the right red or white. His all time favourite multi-purpose woven needle was a 70 denim (Schmetz makes these among others) which he said was the pointiest needle and did a far better job with heavier fabrics that say a 100 (16) universal.
"Which would be easier to nail into a wall," he said, "a fine finishing needle or your elbow?" The larger the needle the more area and therefore force required. Stitch quality is lost.
2. Machines, particularly those with metal bobbin cases "love oil." Without oil the friction of the machine causes the metal to swell as it heats and this causes wear and consequently creates loosening in the parts so the efficiency of the mechanism is lost. Like how old machines rattle.
A good hook oil (one that goes in the bobbin case) is clear, not coloured, and evaporates in the air - this prevents oil build up. He advises "washing the hook" every once in a while and showed me how to do this.
You put a piece of paper towel down in front of the machine and take the thread out. You then put quite a lot of oil into the bobbin case on the hook (the finger that goes around the bobbin in the case), put down the presser foot and run the machine fast for at least 5 minutes. All the little fibers will come flying out of the machine with the excess oil.
I do this to my Pfaff regularly and it really improves my stitch.
OK now off to work.