Great tips from people on this thread! I agree that the thickness of the string and the thickness of the gap make a huge difference on how the yoyo responds and how likely it is to snag. The length of your string also plays a big part in this. Not sure how long your string is for 4a but try shortening your string. I measure from my throwhand extended until the beginning of my opposite shoulder. Essentially, it should probably be shorter than your 1a string unless you play 1a with super short string. When you put too much string in the gap, you run the risk of snags more frequently.
We’ve been discussing this and other ways to improve your offstring throws here! I created a video on it so hopefully this helps!