Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Does yours squeak and make a zipping sound when you pull it backward? Hi,I just bought this last night, and agree with the other reviewers that it seems like it cleans well.  However, when I pull mine backward, it squeaks and makes a zipping sound.  Did anyone else have that problem?  Maybe I got a defective one.Thanks!
Document: I read all the reviews, and decided on the Eureka 4780. I read about the common problems ( pedal hard to push down, hose too short, too heavy, too loud). Maybe they have improved on some things, b/c I had NO trouble at ALL pushing the pedal down. The hose seems plenty long. The sound was not a problem for me. The vacuum came with one bag inside it, plus an extra bag and belt in the box.
I went out today and bought "The Boss" based solely on the numerous positive reviews (almost 500) here on Amazon. I must say I agree 100% with all of my fellow reviewers---this vacuum is awesome! Did I mention that it's cheap too?Considering that there's little to be said that hasn't already been said umpteen times in these sundry reviews, I'll keep mine brief. I will say though that "The Boss" restored my faith in Eureka. Let me explain.
However, beware, this vacuum will suck up anything and everything that comes near it. Small toys, shoe laces, straps, socks, etc, will disappear if not removed prior to vacuuming. It is heavy, but also realize that you get what you pay for. It works well, and will last (my mom has had one for 4 years). I appreciate how well it cleans, but if you don't like to heft a large vacuum, perhaps this isn't for you.
Seems almost like a car where you get max performance after breaking in for 30k miles. Anyway, I don't typically write reviews of this sort, but this vacuum so impresses me, every time I use it, that I just felt I had to share and I seriously brag on our SmartVac and recommend it to anyone who ever asks me how I keep down the pet hair. So thought I would recommend it to everyone else as well.
I think I paid around $130 new. I guess I was pretty lucky to make it last for so long! Considered buying another one, but it sounds like the plastic parts have gotten worse and people are having more problems. I never had to take it for repairs, but maybe I should have when the brush engaging started to malfunction.
I'm glad I read the reviews on the Vacuum before I purchased it because of a few minor problems that have occured. It seems that these problems have been on going for other buyers as well but it doesn't take away from the great sucking power that is hard to beat and the wide base really makes it easier to vacuum so I bought it anyway. It's still a great lil' vac. at a very good price. I'm glad I now own it and hopefully it will last a good while.
I've had this vaccuum for about a month now, and no problems at all. Suction is very good, cleans our carpet very well. One thing is, that it is a pretty heavy vaccuum, but it picks up so well its worth the extra weight. I would definitley reccommend this vaccuum to anyone. The m,ain reason I got this one was because it was so highly rated on consumer [...].
I do use the carpet attachments and setting for our carpeted doggie steps, and it makes them look like new. It's never been cleaner in here. I use it to vacuum the windows, ceiling fans and even the walls and corners. The hose could be longer, and the unit is loud, so I try not to use it late at night (neighbors). I even use it to vacuum our freestanding HEPA filters and our air conditioners (make sure you unplug appliances before vacuuming them).
I bought this vacuum in early 2006 and it is now dead. I didn't use it all that much, maybe once or twice a month as my cleaning lady does the vacuuming (no pets either). I did like it when I did use it. It had great suction, it was self-propelled and overall did a good job. I had the other problems some other reviewers had with the handle release that was hard to push but that didn't seem like a big deal.
The vacuum does have very good suction and it pushes easily. Everytime I pull it backwards though, it makes an annoying chirping sound. Also wish the edgeguard was better, but for the money this is a decent vacuum.
Answer: I noticed that mine does that as well, it also has a funny sound from the wheels when it rolls.  I wonder if that zipping sound is the bristles of the brush rubbing against the plastic housing.