I just bought a set of these LP90's too. I figured it was worth a try with the steals and deals price. Mine also have some of the previously mentioned issues. The 1/2" seems fine. It has light back drag, ratchets smoothly / evenly and the selector switch operates easily. The 3/8" has heavier back drag and the selector switch is a little harder to operate. I suspect that slightly shortening the spring would fix both of those issues. The 1/4" is the most problematic of the three. The back drag is pretty light and the selector switch operates well, but it randomly binds while ratcheting, in both directions, just by turning it with my fingers (no socket on it). I'm not quite sure what to do about that. The spring tension on the pawl seems to be about where it should be, based on the back drag. I opened it up and didn't see any obvious imperfections. It had lube from the factory, so that's not the problem either.
I haven't decided if I should try to fix it, maybe get a rebuild kit for it, or just return them and forget about it. Once I start messing with them and modifying things, I'm stuck with them, whether they're fixed or not. I will say though, that they all have almost zero back lash, which is one of my pet peeves with a fine tooth ratchet. Excessive back lash completely defeats the purpose of having fine tooth in the first place. If anyone has any suggestions, especially for the binding on the 1/4", I appreciate the info. Right now, I'm not very happy with my purchase, even at half price.