if you mean by "dead zone" an area where the ball stops between players out of reach of a man then that happens on all tables
I don't know what rules Tornado is packing in with their tables these days but the "Official" rules, the ONLY "Official" rules in the US or any other country can be found at the link below...these were adopted and adapted from the US tournament rules 4 years ago this month I believe
this link is part of the website of an organization called the ITSF (International Table Soccer Federation)
http://www.table-soccer.org/rules/documents/ITSFRulesEnglish.pdfthe rules are easy to access online at this link and it would be good to save them as a favorite as you get used to playing with them - if you need help interpruting a rule, me and others on this site will be more than happy to clarify what we can and we have access to key Officials if there is clarification needed beyond our knowledge/experience (not likely much

)
if you are asking about ball size thinking to compensate for the gaps so that you never have a dead ball there are no balls large enough used on any recognized table that would help make that happen and frankly you would not want it anyway --- a ball that large would be nearly impossible to score
"Official" rules are often an annoyance for the casual player who has played their own set of rules as they were introduced to the game...just a couple thoughts about that
first, everyone plays by some rules...either ones they or someone they know have made up or by some "Official" set...either way, you have rules - best to recognize that and embrace that fact
second, i am of the opinion, even if you are a casual player, you might as well play by the Official rules...they have been developed over 35 years of competitive play and all are there for good reasons even if you don't understand the logic on the surface...trust those who have gone before you...they aren't perfect and as with all things some people argue about one rule or another and how it should be dealt with but all in all, the Offical rules are really really really good
now, with that said, playing by your own rules or making up your own games is totally fine...the idea is for you all to have a good time and your own rules are fine just recognize that they are just random decisions by you and/or your friends and don't force them on other people when you play at a bar and don't expect them if you decide to try out a tournament...when you go to a bar, try and find what rules they are playing by or is a team by team thing and you work out your aggreements before the game starts
this is the advantage of Official rules everyone can go see any time but still, again, foosball should be fun for you and your friends so do what is fun understanding you are making things up
hopefully this gets at your questions, if not, let us know and me or someone here will try and clarify