There are a couple of ways you can try to unclog your vacuum tube if necessary. All you need are the right tools.
Step 1 - Use a Shop Vac
Use a shop vac. Shop vacs have a lot more power than the average vacuum so unclogging your tube might simply be achieved by setting the shop vac to suck in reverse.
Step 2 - Try Lumber Strips
Use lumber strips. If the shop vac doesn’t do the job, get an 8-foot section of 1x1 furing strips and push them into the tubing and then push them through to the other side to clear the tube. As one bit of wood goes through, the next piece will get pushed in to move the one before it along.
Step 3 - Snake it Out
Use your snake to dig into the tubing until you feel the clog. Grab onto the blockage and keep manipulating it until you feel it loosen. Once you see the blockage, you can use a straightened wire hanger that has a small curve at the end to reach down and get it out.