The 1000 ohm resistor solution worked and I was able to change the decoder address.  Thanks for the tip, now all I need to complete the job are working couplers.

I finally swapped out the circuit boards and it works! I now have two DCC locos. Now I need to install some couplers since the old ones never reappeared after my initial disaster.

On another front (which I have seen discussed elsewhere), the Bachmann decoder doesn't seem to easily allow you to set it to a new address. According to Digitrax, a resistor needs to be placed across the programming track to get the decoder to recognize commands. Do they mean to connect one end of the resistor to one rail and the other end to the other rail? That's how I interpret "across." Please let me know if this is right. (A diagram would help!!)

Got back into my mess.  Managed to solder the loose wire to the motor and more or less get everything into proper place.  Somehow, in the previous disaster the couplers and some spacer washers got lost, but with the shell back on, it's running again on DC.  Later, I will try to swap out the circuit board. 

I have cleaned the wheels and the track, but will check both again.

Since my last reply, I pulled out my schematic of the engine and I assume you mean the wipers in the trucks.  I am hesitant to take the engine apart (prior bad experiences).  Is there some way to fix this without taking it apart?

Yes, I have a multimeter.  The wipers are located where?

I have a new DCC equipped F7A to replace one that recently broke.  It ran sporadically when I first got it on a layout which had given me no previous problems.  Current was going to all sections.

Got out some older track and ran the loco on it for awhile.  Looked like it was broken in, but back on the layout it won't run.  Tried it back on the other track with no luck.  Cleaned all track.  No go.

Occasionally, the headlight will come on, but never fully.  Somehow juice is not getting to everything.  Are there some "fixes" which I can attempt?  I really liked my old F7 and hope this one will be just as faithful, but not running, it's just a doorstop!!

Disaster!!  While working on the F7, I managed to knock out several small screw backings and disconnect a wire from the board to the motor.  I now have it in pieces to try and reconstruct later.  My advice is to be very careful or just leave well enough alone.  N scale engines are extremely small.

It came with a train set, but I have popped off the shell and know that it has a circuit board on top and appears to be the "3rd" type of F7 diesel.

My F7 looks like the newest type, but the board on it is slightly shorter and is listed as DC, but if the motor is isolated, swapping out that board for the newer DCC one should work.  I'll let everyone know after I try it.

Thanks for the video link.  I've seen it before; it appears to deal with the Plus and Spectrum versions, not the one with a circuit board on the top of the frame.  What I really want to know is whether or not the motor is isolated so that replacing the existing DC board with a DCC board will work or if further work (like in the video) is needed.

On the newer F7A diesel, is it possible to replace the DC board with a DCC board and, if so, are there any other modifications that need to be done to operate on DCC?