Wiring Locomotive Motors in Series

Follow the brown wire down from the reverse unit... it should be connected to a yellow wire and a blue wire on the terminal block. If it is, disconnect two blue wires from the terminal block and connect them to each other(or, disconnect two yellow wires and connect them to each other if that's easier). 

That's it!

My MP-15 has a factory switch to change from series to parallel....check  underside first. If not I have a diagram I can post from home, 

ADCX Rob posted:

Follow the brown wire down from the reverse unit... it should be connected to a yellow wire and a blue wire on the terminal block. If it is, disconnect two blue wires from the terminal block and connect them to each other(or, disconnect two yellow wires and connect them to each other if that's easier). 

That's it!

Thanks Rob.  So the "Terminal Block" would be the square piece just left of center, in the photo ?    The two Blue wires OR the two Yellow wires that are heading down into the terminal block are the ones you are talking about, correct ?   Either set, the blue or the yellow can be cut and spliced ?

This picture may be a bit clearer.  I didn't remove what I think is the E-Unit, which is toward the right.

If you look at the terminal block- the translucent white plastic square - you can see the copper bus strips inside the block. In both of your pics, I can't tell if the yellow & blue wires are plugged in to the same bus because the view is obstructed. One more picture from the other side should confirm if the yellow wires are connected on the same strip or not.

From the top, left to right, here is what i see:

Yellow-Blue-Brown
Blue-Yellow-Blue
Black-Black-Black
Red-Red-Red

ADCX Rob posted:

From the top, left to right, here is what i see:

Yellow-Blue-Brown
Blue-Yellow-Blue
Black-Black-Black
Red-Red-Red

Rob, thank you for your patience.  Here are more views.  I loosened the terminal block from it's two clips.and took these photos.  I think they are a bit more clear.  

I can see the brass strips on the underside and here's the way I read it starting at the top of the picture, left to right.

Yellow - Blue

Blue - Yellow

2 Blacks - 2 Blacks

2 Reds - 2 Reds

The brass bus bars are running left to right across the picture.  

Much Better! I am now seeing:

Yellow-Blue-Brown
Blue-Yellow-Blue
Black-Black-Black-Black
Red-Red-Red-Red

So my original instruction stands - disconnect the two blue wires from the terminal block and connect them to each other(or, disconnect the two yellow wires and connect them to each other if that's easier).

Thanks again Rob.  I now have tomorrow's job all lined up with no guessing !!

Got the wiring done.  Loco performs much better now.  No jack rabbit starts.  Speed is reduced to a manageable level for grandson #1.

Thanks again Rob.