!!!ALWAYS KEEP THE AREA WHERE THE CAP & BODY MEET - CLEAN!!!

TRY THIS FIRST - Before following the Instructions below – Please clean your container with alcohol or the purest chemical free cleaner you can find – After cleaning try putting wax (wax paper, candle wax – Even car wax) around the areas where the cap and the body meet. If the cap does not slide up and down to your satisfaction – Follow steps below……
  
First you need to get Wet/Dry Sandpaper (used to be called Emery paper).
I believe this is Norton’s brand but other companies have it as well. Buy the 320 extra fine & 600 Ultra fine grain ratings paper.

Once you have this in your work area - take caps off completely (usually the inside of the cap isn't the problem – it’s the body of the container where the cap slides on - On the 1.3 Tightvac this is a 1" surface that is indented separating it from the main body of the container - thus making it easy to sand.

Start with the 320 extra fine and start sanding around the entire circumference of the container. I recommend spending at least 5 minutes carefully sanding this area - making sure to do it carefully so the sand paper doesn't accidentally scratch the main body of the container.

When phase 1 is completed then finish the job with the 600 Ultra fine by sanding carefully around the 1" area for about 2 to 3 minutes.

When this is finished, clean the container with a damp rag &  let dry - then use wax paper, candle wax or even car wax (If you are not eating out of the container) or any wax you may have on the sanded area and Bob's your uncle.

This should solve the problem.

The more you sand the easier the cap is to slide on & off. It is important to make sure the inside of the cap is clean and apply wax to this area as well. In some cases the inside of the cap may need sanding as well - in any case this will ensure your Tightvac to open & close until the whole container falls apart!!!

GOOD SANDING.