Type cheat (slow down ball movement):

Look in the Zuma Deluxe!levels folder for a file called levels.xml and open it using Notepad (make a backup copy of it first).

Go aprox halfway down until you see the following line:

lvl11 means level 1-1. So, if you want to slow down the speed of the balls for this level, 

all you have to do is change the speed setting from 0.5 to 0.2 and then exit and save.

If you're stuck on a higher level, say 12-7, and then just go a few lines lower to where it says lvl127

and change its speed setting to 0.2 and save.

Note don't confuse the lvl11 line above with the level11 line on the same page.