You are going to need to unscrew anything that can't be unplugged.

Before you switch out the coil, you have adjusted the EOS perfectly? (cleaned the contacts too) There are other threads here about flipper rebuilds, but seems to be a commonly misunderstood procedure. Usually it's not the coil, it either works, or it doesn't. Lack of power is usually something out of whack that can be corrected. Yes, return spring tension can be a problem. You may need to move the spring hold down (hook) to another screw on the bushing to get that just right. Old bushings that are worn, will rob you of power with too much wobble in the shaft. Also worn flipper links that have elongated pivot holes. Have you read up on this topic on the Pinrepair and Pinwiki websites? An hour's study will really be a help.