You are right, the internal fans are a very snug fit, and thin walled housing means they will bind up with even the smallest misalignment. Something of a mismatch between fan designers utopia and real life.
Spirit level on the drill (plus a bit) if you are worried. Installing a new fan to old wonky duct is the trickiest, I recently had to grind out plastic inside the duct wall to allow one in without binding.
You are right, the internal fans are a very snug fit, and thin walled housing means they will bind up with even the smallest misalignment. Something of a mismatch between fan designers utopia and real life.
Spirit level on the drill (plus a bit) if you are worried. Installing a new fan to old wonky duct is the trickiest, I recently had to grind out plastic inside the duct wall to allow one in without binding.
