This pin can be troublesome, especially on the Ferrari calipers where the later build dates saw some economies built into these calipers. They used a hollow roll pin that is prone to corrode and break away. I've never seen that pin on a 914 caliper but, some of you have upgraded to the 308 calipers over the years. That said, this is a very common problem on 914 calipers.
This fix puts a hardened steel piece in it's place and should be a lifetime fix.
Follow along...
The first thing you'll want to do it get a punch on the very center of the broken off piece. This is where the Ferrari versions have a slight advantage. With the hollow pin, you will easily center your bit.
If you're lucky the pin will still have some travel left in the cavity and push a tad further in leaving a nice depression for the drill to come in nice and straight. Or... you'll get a nice dimple in the center of your broken pin.
Next, get a 5/32nd drill bit and put it in your drill press. I would encourage you to use a drill press for this. If you don't have one, ask around... one of your friends probably does.
I use a press clamp to hold the caliper and to act as a block to keep the back 1/2 of the caliper level. Slowly start to drill into the pin cavity.
Checking to make sure you're still on center...
Drilling away at it.
You should feel it in the press handle when you get to the bottom and, if you're right on target, you should get the remainder of the pin on the end of your bit.
Nice clean hole... ready to put the drill bit back in but, not like you're thinking.
Measure your good pin. Most pins hang out by 15mm.
Remove the bit from the drill press and insert it into the hole. Mark the bit where 15mm shows.
Next, cut the bit off using a Dremel with a carbide wheel or a hacksaw. Then mix up a small dab of JB Weld (use the cut end of the bit to mix with). By using the cut end of the bit, you now have a nicely finished end on your pin (what use to be the end of the drill bit). Drop the bit into the hole being very careful with the JB Weld. No need to get this stuff all over.
Work it up and down in the bore. If you did a really good job, there should be a bubble in there you'll have to burp to make it seat (tip: twist). Once it seats, clean up the excess JB Weld and let it sit for 24 hours. Your caliper will be better than new.
Hope that helps...