There are two spring-loaded screws on the top of the machine. One on the right (under the bobbin winder lid), and one on the left (built into the bobbin winder tensioner). Push down, then turn a quarter of a turn. You'll know you're in the right position if the screw pops up.
Once you get inside, you can clean and oil, and adjust the presser foot tension. Here's where that adjustment is.
The copper colored cylinders are the basting mechanism. Be sure to use this feature every-once-in-a-while, so it doesn't freeze-up.
Here are some diagrams on how to oil your Bernina 930. You can click on the image to make it larger.
#1 upper shaft
#2 eccentric / tracer
#3 and #4 turn stitch width knob to see sliders
#5 top of vertical shaft
#6 and #7 both sides of stitch selector plus 2 spigots down inside
#8 eccentric / tracer
#9 turn handwheel to find hole
#13 feed dog joint
#14 spigot down inside
#15 left side of shaft
#16 right side of shaft
#17, #18 and #20 feed dog linkage
#19 turn handwheel, oil joint as it comes close
Don't have time to do the take-up area. Hopefully, I can get to it later this week.