I make my own stub switches now so I can ballast alomost like regular track.
However, when I use to make regular turnouts [switches] i would paint on the contacts a tiny bit of oil like vegetable oil. I used a small brush.
Anyhow, the glue would not stick to the oil and I could then lay the ballast easily.
I would put oil where ever there was a moving part and also on the areas of the ties that the rails ran over.
I hope this helps :)