It's pretty common on the 1512,1612, and 1712 for the gauge plate to seize. Happens from no cleaning or improper oil being used. I don't think the 1512 has an access plate for lubrication. but I don't see a lot of them anymore. The best thing to do is turn the slicer over and soak the guide rods in food grade oil, after a soak take the adjustment knob off. Ther should be a shaft with a nut on it, use a wrench or crescent to turn the shaft and work the oil in, it may take several tries. If it does have an access plate this process is much easier. If you have any pictures I can tell you for sure, I also have a PDF manual for this if you don't have one. Hope this helps!