Hi and thanks for using JustAnswer.com.
You will need to lightly stain the light spot. Select stains that are of the same color family as the darkened paneling. Mix them using an eyedropper and count the drops for each color. Adjust the number of drops for each color until you get the right shade. It might be something like:
4 drops weathered grey plus 8 drops honey pine plus 1 drop mahogany. You get the idea? Test the mixes out on a piece of scrap lumber that is close to the light cypress, or buy a piece of cypress that is the same color as yours.
Thin the mix with 2-3 parts paint thinner to 1 part stain mix. This will prevent getting dark spots at the first point of contact. Use a paper towel to apply-rub and spread quickly.
Repeat if necessary. Each subsequent application will darken the effect.
I hope that this information was helpful to you. If it was please remember to click "ACCEPT" on your screen to make sure that I am paid for my efforts. By clicking ACCEPT you are not giving up your ability to ask more questions pertaining to this subject, and I will be happy to respond to these as well. Please take a moment and leave feedback, it is very important!If I exceeded your expectations, a bonus is greatly appreciated- it's easy to do when you accept an answer. Or you can come back and add a bonus at a later date by using the "bonus" button at the top your question page.
General C&ontractor
35 years of troubleshooting construction, remodel, component & material failures. What to do next