power it up and see how it runs on full 6V, if it seems slowish, try 12 [momentarily wink ], if it screams on 12, just get a 12V replacement instead of goofing with reducers

related: someone gave me some 24V fans [aircraft or marine] long ago and I checked them recently on 12V to decide their usefulness for daBus - perfect speed at half voltage, very quiet and they'll last longer thumbs_up

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot