The posts are different diameters. I have both. I took my Eagnas clamps to a machinist and paid him to make and attach post to the PN 1012 heads to fit my Alpha machine. I use them only to string polyester strings now. After about 40 stringjobs, the Eagnas clamps wouldn't hold the multifiliment strings (they'd slip right through). They work great on poly's though. The Alpha clamps work with both, but poly's are hard enough that they'll eventually wear grooves in you clamps.
Hi Steve: Although I have a different machine than yours, fortunately the Eagnas 3 tooth clamps fit my machine perfectly. I have used them for a good # of racquets so far, and so far they have been holding up. The only thing that ever bothered me was that when I received them, one was new, and one was very much used, as it was all marred up, and although both looked the same, the metal on the used one looks duller, and the adjustment wheel was a different ribbing on the end from the other one and the used one adj. wheel is chrome plated,and marked up. One must be from an older stock, that someone probably used and marred it up, and returned, and I ended up with it. Because of poor cust. service that I always heard about, I just decided to use them anyways, and never had a problem with slipping, and have used them a decent amount so far, I use the 5 tooth clamps that came with machine for 16g, and the 3 tooth for 17g. I mark the wheel with a sharpie line on the top of the adjustment wheels on both sets of clamps, so I know where the clamp should be set for the most part(I know some strings can be a little different, but this does work) . The line also allows me to see if the adjustment wheel moves at all, as it sometimes can(on both sets of clamps), and I just be sure that the line is always on the top.Anyways the eagnas clamps I received have held up so far.They get used primarily with polys, as I have more 17g. with that type of string.
After reading this post,I took out the 3 tooth, and adjusted for the 16g. for a string job of all VS gut, and just finished it now, and the clamps worked fine.(This was my 6th all VS gut job this week! Very unusual for me to get this many all gut jobs in 1 week, as someone just dropped off this one this morning to make # 6 in 1 week). Possibly you got an older series type clamp that caused them to slip after so much use, but these are going ok for me so far.If they do start to give problems, I'll let you know.