Quoted from robotron911:
In furniture repair, if there is a dent or gouge in UNFINISHED wood you simply apply a damp paper towel and a hot iron and steam it out. The steam will exand the wood fibers and many times you can completely remove the damage.
You can certainly remove a dent with steam, but not a gouge.
When a gouge occurs, the wood fibers are gone. So we can't expand them because they are no longer there.
Even with a dent, if you can see that the wood fibers have broken, you won't be able to expand them without the broken fibers looking darker when you stain - accenting the repaired area. So even if you puff the fibers back up, you will still have to sand past the broken ones.
A ball trail (let's say it's worn into the shooter lane arch) happens where the clear coat has worn through and now the ball is wearing away the wood fibers.
The wood is worn and the remaining fibers are filled with black coil dust.
So if you think about it, steam won't help us in a ball trail repair:
1. The wood fibers have been worn away, so there are no compressed fibers to expand.
2. The remaining wood fibers are broken and "rough".
3. The wood has been soaked with sealer before screenprinting, and then cleared over in the final step. This makes it not absorb water evenly
4. Black metal dust has contaminated the wood fibers.
That leaves us with sanding down to undamaged wood (removing the coil dust in the process), or filling the wear and then painting over the filler to match the surrounding playfield.