How to remove the hook guide

A quick learner from Huntington NY says:
How do you complete step 1? How do I remove the old hook guide? I tried to reverse the above installation instructions, but the hook doesn't release from the underside of the track base. The track base cannot be removed or lifted.
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Tom from SWISCO responded:
I'm sorry, I'm not sure what it is you're referring to. Was there a specific SWISCO product you were looking at? If so, can you give me the part number? Pictures of your project would also help.
A quick learner from New York says:
Shower door guide Swisco no. 10-139
10-139 Shower Door Bottom Guide Instructions
This product guide describes how to install the SWISCO 10-139 shower door bottom hook guide.
Step 1
Slide the shower doors open to one side of the tub. Remove the old shower door guide.
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That's all it says: "remove the old shower door guide". It doesn't explain how. The guide is hooked under the shower door base and floats along there keeping the door from swinging out. As you can see on the part, the bottom is curled up so it grabs onto the inside lip of the base.
Door track
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Tom from SWISCO responded:
Ah, thanks for clarifying. You will want to unscrew the guides, slide them to the side away from the shower door, and then unhook it from the track. To install a new guide, you just reverse the process.
A handy person from Maryville, TN says:
The picture looks a lot like the bottom hook guides on my shower door (which need replacement) however there is nowhere along the length of the base track were it will disengage. I think I will have to remove the doors and the bottom track to slide the guides out and see what I have to be able to order a replacement.
The shower door was installed in 1990. does this date exclude your products applying to my door?
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Casey from SWISCO responded:

Hello,

Our shower guide was not designed for doors made in a particular year. As long as the style and specifications match up with your guide, you should be good to go. We've also included our installation guide below. Thanks for posting. 

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10-139 Shower Door Bottom Guide Instructions
10-139 Shower Door Bottom Guide Instructions
GUIDE
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