You don't want the flat spring type. For a very smooth action get this. No fitting required. This will fit the Colt, Uberti, and the Pietta and clones.
Wire-Type Springs (Stock No. 32294-32296) fits: Colt, Uberti, an most clones
https://www.gunsprings.com/index.php...6#top-products
The hand spring should be replaced. That appendage on the hammer can be removed from the hammer. The flat spring is pressed in and can be removed. The spring needs polished or replaced. This part is usually broken before the others. I don't see the main spring/hammer spring. If the main spring is the least pitted I would guess it will go next. Before you buy one, and if you have the tools, I would polish the mainspring. It is a spring so don't get it hot. If you cannot hold it, dip it in cold water. I routinely grind the mainsprings into an hourglass shape, polish/sand/buff ALL scratches and marks away, and the result is a soft hammer pull, better trigger, and can set off any primer.
Buy some 400 grit and 800 grit sandpaper. Get a piece of glass (super flat and hard) and rub the flat side of the parts on the 400 until rust is gone. Finish to a nice shine with the 600.