It's not really hard. I ordered a spare spring and catch from Kel-Tec just in case it didn't work out well - I didn't need them. Now I have some more free spare parts.
Beach shows how to do it here:
http://www.ktog.org/cgi-bin/yabb2/YaBB.pl?num=1201577117
Beach's directions include removing the frame. I was able to accomplish the task without removing the frame.
You will need a curved hemostatic forceps (just like the one Beach shows). You should be able to get a pair of these at a well-stocked hardware store or possibly a Lowes, Home Depot, Harbor Freight, or even online.
(
http://www.atlanticmedsupply.com/shopdisplayproducts.asp?id=232&cat=Forceps )
They are about $7. They come in really handy for a lot of things. I have a curved pair and a straight pair 5-1/2" long.
Although they are a bit bigger and clumsier and you can't clamp them, a pair of curved long-nosed pliers may also work OK.
It's easier than it seems (it took me less than 10 minutes).
---------------------------------------------------------------------------
Removing old catch:
1. Remove the magazine.
2. Unload the chamber.
3. Pull out the assembly pin and remove the slide.
4. Remove the ejector so it doesn't fall out and get lost.
5. Looking inside at the catch from the top/rear, the spring is clearly visible. You can see this easily with a light shined in from the top toward the catch.
6. The bottom of the right (straight) leg of the spring is in a channel in the right side of the frame. Pop it out of the channel with a small screwdriver.
7. Reach in with the hemostat and clamp it onto the spring. The top (bent part) of the spring is under a channel in the frame. Push downward and at the same time pull toward you to get the spring out of the top channel.
8. Once the spring is free from the top channel pull the spring up and out of the catch.
9. Slide the old catch out of the grip.
------------------------------------------------------------------------
Installing new catch
10. Clamp the hemostat on the STRAIGHT leg of the spring near the top.
11. Slide the new catch into the grip.
12. Hold the catch all the way to the right.
13. Insert the CURVED leg of the spring into the small hole in the top of the catch.
14. Make sure the spring is down in the hole far enough so the bent top of the spring will have room to fit below the top channel of the frame. At this time just put the spring into the hole, don't try to slip it up into the top channel of the frame.
15. Release the spring from the hemostat.
16. Hold the catch as far to the left as possible.
17. Clamp hemostat onto the STRAIGHT leg of the spring just above the middle of the leg as close to the end of the hemostat's jaws as possible.
18. Pop the bottom of the straight leg of the spring into the right channel of the frame (you may have to pop it out of the hemostat and into the channel at the same time). This is the trickiest part. I was lucky and got it on the first try.
19. Insert a small screwdriver up through the bottom of the magazine well.
20. With the blade of screwdriver inside the bent top of the spring, push the spring up tightly into the top channel of the frame.
That's it - you did it!
Bobo