How to remove shear blocks in a Single Hung Vinyl Window

I find the shear blocks supporting the upper sash on both sides of the window frame. They are just blocks with no screws. I don't know how to release these shear blocks so that I can take down the upper sash for repairing.
Please advise and thanks in advance!
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On Nov 27, 10:48pm, snipped-for-privacy@yahoo.com wrote:

Just a thought...
On my Double Hung VRW, there are blocks in the top of the track that prevent the lower sash from opening too far and hitting the "grab bar" of the upper sash.
These blocks just pop into the track and can be removed by prying them out with a large screwdriver slipped in from underneath.
I know this because I took mine out of every window and cut them shorter. I could find no reason for needing 1 1/2" of space below the upper sash's grab bar. 1/2" is more than enough. An extra inch of open window may not amount to much on an individual basis, but with all the windows open, that's over 3 square feet of extra breeze. Considering the amount of "open" you lose when you install VRW's, I wanted to get back as much as possible.
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