Apparently, Mike Dudek at http://www.irollmotors.com/ sells repair ferrules that I think are locked on by a screw. There are 2 shaft sizes so you'll need to know that in advance, although he'll likely know which you need from the Volvo model you have. I have something similar as standard on my Saab 96. They are locked onto the shaft by a screw just below the wiper arm connection. There is a flat on the shaft.

Mine does the same and I couldn't get the wiper back on the post with out using a 6" long block of wood to prop the post from the inside so that I could "home" the blade holder.

A screw will work, but if the wiper comes off then you will once again need the prop.

Klaus
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Always willing to listen, just not able to take direction.

Sorry guys, i should choose my words more carefully as yes i did mean the shaft and not the complete post with retaining nut. The "little knurled hat" had come off with the wiper arm when i took it off to replace the windscreen and having read your opinions i realize that the little knurled hat is no longer a press fit and i need to find a way to make it so as i dont want the wiper arm /knurled hat assembly to work its way off and fly off into scenery. I will consider the drill/tap method. Thanks again. David

Are you saying the shaft can be pushed through? Like others said, it would be very obvious if the post pushed through.

I'd guess you just mean the shaft which is only held in the post by an aluminum knurled "hat" (wrong term, but I can't think of it's proper name at the moment) which is press fit onto the shaft. The wiper arm fits onto the hat. If the hat has loosend up, the shaft will drop into the passenger compartment and you will loose the wiper and hat somewhere on the side of the road.

A possible fix is to drill and tap a hole through the wiper arm into the shaft.

Can we assume from this that the rubber seals and large nuts are missing on both wiper posts. No way they should push through with the nuts on.