I do this repair quite frequently because I like to buy junk gang cars and fix them up.
I use short machine screws as replacement posts. I think 4-40 screws work the best, although I have used 3-48 screws too.
Trim the posts flush with the deck. I use an Xacto chisel blade for this, shaving a bit at a time so the blade doesn't mark the deck around the posts.
Drill the proper size hole right through the spot where the posts were. According to a chart I found online, 3-48 uses a 5/64 drill, 4-40 uses a #43.
(I use a drill press to get the hole nice and straight)
Then carefully tap the hole.
install the screw from the inside, until the head is flush with the casing.
There is plenty of clearance to leave the head in place.
I use trial and error to determine the length of the screw.
Nylon screws are easily trimmed with a pair of linesman pliers after being screwed in.
If I am using a metal screw, I determine the length, and remove it from the case before cutting.
Thread a nut on the screw.
It will act as a chaser to clean the threads after making the cut.
Given the small cross section of the screw, these are also easy to cut with a linesman pliers.
After cutting, I file the end of the screw smooth.
Removing the nut will chase the end of the thread.
Re-install the screw.
It took me longer to write this than it actually takes to do the work.