Ok, Take off the pan there are little e-clips with linkage connecting the out side leaver to the actual VB. These are infamous for falling off. This problem/symptom will give you that leaver locked up feeling. If that doesn’t work take the VB completely out (it simple really) just don’t over tighten the bolts on the installation and keep track of what bolts went where cause some of them are different lengths. Once the valve body is completely removed thoroughly clean every passage out with brake or carb cleaner, while working the Valve back in forth. Please note I have never seen the valve its self lock up that hard. I think your issue is the internal linkage.