If you are using the mount at 35 degrees latitude and the front latitude screw won’t lock, this is normal for the CGEM. Here’s why.
The CGEM has two latitude adjustment screws that bear against the lowest part of the equatorial head, allowing fine adjustments in latitude.
The front latitude screw is meant to lock the mount for high-latitude users north (or south) of approximately 40 degrees latitude. It prevents shifting of the head in the direction of possible unbalanced weight. At high latitudes, this is towards the back of the mount away from the counterweight.
Above 40 degrees both screws can be locked to hold the head in position.
Below 40 degrees, the front screw won’t lock the mount because of its length and the casting curvature. But that’s okay, because the weight of the counterweight and bar will pull the mount down and hold it firmly in place against the back latitude adjustment screw when it’s positioned for lower latitudes.