Brother LS3- C51-050

[Woolies]

I've got a Brother LS3-C51 but for the life of me cannot find a manual. I know there are some similar machines out there (techsew, consew, etc...) and I've found info on those ones which has been helpful but my machine has a few different parts and I am wondering what these are. Maybe it's an easy answer from some of you experts but I'm a newbie. 

I've attached a photo with arrows indicating the 2 parts. The black one turns and has a white divot dot on top. And the silver one screws up and down. What are these for and do I need to oil them or set them or???

If anyone does know where to get a manual I would greatly appreciate it! 

Thanks so much!

[Wizcrafts]

Most likely the big black thumbscrew is the primary rear foot pressure spring adjuster. The spring would be a long, flat, heavy steel spring running inline with the back of the machine. The adjuster on top of the head is probably to fine tune the pressure on the inside foot.

[Woolies]

Thanks so much Wizcrafts- I will check and see if those things happen when I adjust. 

[Gregg From Keystone Sewing]

Consew 255RB Owners manual

See above, black dial is part of the lubrication system, the silver knob is fine adjustment for the presser foot pressure.