I have a 1990 Force 120 that I'd like to replace the tilt pump valve on due to a small leak down. Are they pretty easy to change out?, 4 mounting screws out, replace with new, 4 mounting screws back on? Just not sure if something on the inside is going to fall out. I'm going to replace it while it is on the boat upsidedown. Natually I will have to re/mount the 4 lines. thanks for any input on this.