I had to strip the paint off a recently painted boxcar because I didn’t like the color.  I used a bath of 99% isopropyl alcohol like I always do in such a case.  Here is the result on the roof walk.

[attachment=36576]

I have never seen that.  This is a resin kit.

I tried stripping paint off a resin 3d printed part using 99% alcohol and 2 hours in the alcohol and the plastic was like wet pasta.

Weia!

Guy,
what you can do if the walkway is still soft:
- turn car upside down onto an plain pad, so it will lay on it's walkway
- add some weight into the car inner direct to the roof
- the weight(s) should be long and narrow and bearing directly, in this upside down status, over the walkway
- wait until the alcohol has evaporated out of the resine and hope (and pray) the walkway will become straight again


Worst case:
Make a new walkway.


Lutz

Guy, 
      While you may think this is a disaster, the walkway can be fixed, but I really like the looks of that car as it is now (with the exception of the walkway. I think some weathered black data and heralds for any road would make an interesting looking car. Actually it looks like a good candidate for a GERN box car as it already has 3% more weathering. 
Charlie

Thank you guys for the reply.

Charlie :  this could be a good suggestion but here is what I have in mind :

[attachment=36583]

The prototype is actually at Exporail in St-Constant, QC.

Great looking car Guy. A good project for sure.  I actually owned a CP box car for a few years. It was newer and I believe 60 foot. 
Charlie