First off you should go buy a good tablesaw book - I recommend the one by
Kelly Mehler and/or Jim Tolpin. I have them both and they are both very
good. I'd go with the Mehler book if I chose just one.
In these books they cover extensively the proper way to align a tablesaw, so
if you get the book you'll be set.
At any rate, aligning the blade parallel with the miter slot isn't too
tough, IMO. To check it however, make sure you are using the same tooth on
the saw blade. I have an alignment tool called the TS-Aligner, Jr. (do a
google search for the website), which employs a jig and a dial indicator.
This allows very precise measurement of the alignment. I've also used a
simple combination square, referenced off the miter slot, to measure the
difference. Either way, measure a tooth in the front of the blade slot, and
then rotate the blade by hand and measure the same tooth in the back. If
you don't rotate the blade, any variations in the blade itself, etc. will
appear to be variations in the miter slot/blade alignment.
If your saw is truly out of alignment, it is definitely NOT a cause to
return the saw. You need to unbolt the cast iron top from the saw and move
it. On my Unisaw there are 4 bolts that do this. Sure, it's a pain, but it
isn't really that difficult. I'm sure your manual covers this.