Just by what is happening in the video. It appears that the 3rd reel is dragging on something.
Or it needs lubrication. This might have something to do with a shorter spin cycle.
Test the reels spin by removing the entire reels unit out of the machine. Pull the index stop arms back out of the slots. Spin all 3 reels by hand at the same time. Note any reel stopping sooner than the others.
If the reels appear to be working properly, remove them and set aside. Block up the reel chassis on the right side around 2 inches. Apply a penetrating/cleaning oil to every shaft and moving part pivot point. Also check any ratchet wheels, they should turn free and easy. Let set over night. Wipe clean and re-oil with 3 in1 machine oil with the mechanism still propped up. Let stand for a few minutes then remove excess oil, reassemble and replace.