Husqvarna 3900 what year is the electronic 3900 husqvarna

The oiling instructions should be in your owner's manual. Unnecessary or excessive oiling could cause permanent damage to the machine.

try this link and see if it's the right manual for the machine
http://sewusa.com/Sewing_Machine_Manuals/Viking_Manuals/210_230_250_Instruction_Manual.htm

2003 - I think the second half of the year.

Sounds like the feeding mechanism is messed up. If turning it on and off does not resolve the issue, you'll need to have it serviced by a certified Husqvarna Viking service technician. If you are the original owner it may still be under warranty. SE's have a 5 year electronic parts warranty and 20 year mechanical warranty. However, you will need to have it serviced by a Husqvarna Viking dealer. You can locate a dealer near you by visiting the husqvarna viking website and clicking on the Dealer link on the left-hand side of the page - http://www.husqvarnaviking.com

Good luck.

The overload message is usuall due to a bind in the mechanical function of the machine. When the motor has an extra "load" caused by something like a tight belt or dry bearing, it "overloads" the motor and the error message is displayed. It is doubtful your problem is computer related. Either way a trip to your service tech is required. If you continue to sew with it, you do run the risk of possible damage to some other parts of your machine. The computer portion of your Husqvarna is guaranteed for 5 years and the mechanical parts carry a 20 or 25 year guarantee depending on when you purchased your machine. A copy of your bill of sale from a Husqvarna Viking dealer or a stamped warranty card is the proof of purchase needed to obtain warranty replacement of parts. Labor is only guaranteed for 1 year.

if the capacitor is still legible, it is a simple task to unsolder the old capacitor, read the label and source and solder in a new capacitor. Capacitors do blow once in a while...

An electronics repair shop should not charge more than $10 or $15 to replace it if you are not up to the task of soldering...

I would take it back to your service tech or choose another. It may be something simple that needs replacement, like a new cord. (or . . .)

Also, before thinking of buying a new machine, I would get another opinion.

You will most likely find that ALL of the "better" manufacturers; Bernina, Husqvarna, Pfaff, will not sell proprietary parts to non-brand dealers. Ultimately, this protects the customer.
With that being said, chances are the problem you are having is NOT a bad circuit board, but a bad power supply. But, since you don't trust your local dealers, find a dealer that is not so local. A two hour car ride is going be a lot cheaper that replacing the wrong part, and NO dealer will return your money on a part that the customer diagnosed as being faulty. I assure you, a Viking dealer somewhere will help you with your problem. You might want to try a Pfaff dealer. They can sometimes obtain Viking parts.
I would try replacing the power supply first. Its a cheaper priced part, and more likely your problem. Its also easier for DIY'ers, but extreme caution must be taken to ground yourself to the machine. Static is always a concern with electronic sewing machines, and even more so this time of year. Proper grounding equipment should be worn while performing any internal repair or adjustment in any electronic machine.
As far as replacing the circuit board yourself, if necessary, also be very careful when disconnecting and reconnecting wires. The connectors are very small and bend easily. Also, care should be taken when tightening screws. Overtightening can cause faults within the circuit board by cracking the solder paths or just plain break the board.