My brother Se 400 which is only a few months old just started running really slow. When I disconnect the foot petal and do the manual botton "the arrow button" it still runs slow. I don't think it is the foot petal because of this reason. What are your thoughts on fixing it?

I would have thought the maker could supply parts for everything they have sold. Contact them direct. Make sure your repair shop is an authorised service centre.

https://www.brother.ca/en/placing-an-order

1. Set all tension to 1.
2. Remove all the thread.
3. Disengage the trimmer.
4. Turn it by hand.
5. If it is free, try your foot petal again. It it runs, learn how to thread. It only takes one mistake to bind up the machine.
6. If still slow, borrow a foot petal (or take to a shop and use one there). If still slow, bad motor.
7. It it does not turn free, open the case (but look on Youtube first):
8. It might need lube. Use a LITTLE BIT of oil on the inner bearings but none on the motor.
9. Cutter too tight. Loosen.
10. Wad of thread inside.
11. Something bent.
12. Out of timing. Again, see Youtube.

If you mean the foot controller, then the T/FC-322 is a substitute that should work. It's listed as a replacement here: http://www.sewingmachinesplus.com/234522001.php . The manual for the NX400 gives the foot controller as XC1154-051 . Brother changes the part number often but the wiring remains the same. Another substitute controller is available here: http://www.sewingpartsonline.com/foot-control-w-cord-brother-xc6651121.aspx .

The F04 message may mean there is an internal failure. This probably needs to be fixed by a Brother authorized repair person.

I wish that I had better news for you.

Cindy Wells

possible problem in foot control or speed control
as it less than a year old it will be under warranty so take it in to a service agent and have it checked under warranty

look for the speed control knob. turning that should make it sew faster. usually it is quite big.

Yes it does sound like a faulty foot control. The power cord is probably fine, you just need the controller. Ebay is a good source for parts.

Remove the foot pedal before you turn it on.

is there a wheel inside the hand wheel on the right?  tighten that by holding the hand wheel and turning the inner wheel away from you.  let me know if that doesn't work!

Set machine to wind the bobbin to check for how fast the machine will run. I believe it will run fast or slow according to how hard you depress the foot control. If it runs fast and slow you have a problem in the machine. Most likely the machine, if turned by hand, is hard to turn and it needs to be professionally serviced. before it is ruined.
sewman7

F04 is foot control error. It is probably a bad foot control, but it may be the plug in on the machine or a circuit board.

You can run the machine without a foot control for now; just unplug the foot control from the machine and use the Start/Stop button like you would when embroidering.

Before replacing the foot control, you should bring the machine to a Brother shop and try a new control. If the new one works, then the control was the problem.