...and with a small dowel...

I use a i/2" wide piece of hard 1/32 balsa rounded.  Makes a great flat piece to push the tape onto the flap.  As for electric, they don't get oil under them but neither do the IC if you really smooth out the edge and put a light coat of clear over the seam.

I am still looking for a good way to seal imbedded flaps.  Maybe somebody will make a "Hinge Line sealing tape" with no sticky stuff in the center.  But, since payback on investment in manufacturing would be about 200 years you would have to be crazy.

Ken

I have heard of "taping hinge lines",  if elevator or flap hinge lines have too much space between them.  How is it done?

   Your hinge line does have too much space in it. Define "too much" as "any at all". With zero clearance, it it binding up, with any, it's bigger than an air molecule.

    Sealing hinge lines is very important, we don't bother flying the airplane without the seals. Usually you use tape, but you can do other things, too, like build them in (which is how Dennis Adamisin did it). This is how I do it:

https://stunthanger.com/smf/stunt-design/hinge-options/msg99465/#msg99465

   The airplane is ideally built with this in mind, leaving sufficient space to easily apply the seal. It's compatible with the single hinge pin, you end up with the tape crossing the gap attached to the pin.

     Brett