I know how to fix that cause I had the same problem and got so mad I wanted to use it for a boat anchor however I have found a soulution and i will tell the world right here right now
ok you will need
1 phillips screwdriver
1 long plastic or wood tuning screwdriver (if you dont have one ask a geek/electronic know it all/tv repairman for one or sand one end of a small less than 1/4 inch wooden dowl into a flathed screwdriver so it looks like a screwdriver on one end)
4 new rayovac maximum plus alkaline batteries (no substitutions)
optinol half a freaking brain
now to fix tha pece of crap
first remove the batterie door and batteries toss the batteries
now on the bottom of the joystick there are four screws remove them with the phillips screwdriver DONT LOSE THE SCREWS.
now turn the unit right side up and pull dtaight up un the joystick the top cover will come off set this and the fire button aside now you should see a circuit board with some buttons on it it should look like this
---------------------------------------------
/ / +=button
/ + / %=variable resistor (blue
/ fire / case white screw on top)
/ + % /
/ up vr1 /
/ /
/ + + /
/ left right /
/ /
/ + /
/ down /
----------------------------------------------
now put the new bateries in and turn on the power waitfor the menu screen to come up PLAY SOME games until the graphics are garbled and the unit becomes almost useless. hit reset as then fire+start+select now you should see a screen with all of the characters (ships guns planets ) from grAVITAR. let it get garbled to no return (all screen un readable) nowget out your trusty tuning screwdriver and adjust vr1 until all of the garbage is gone and then a hair extra (but not to the point where the background is grey with purple stripes) in my case i had to turn it ~1/8 turn clockwise
now put the thing backtogether and have some fun
your welcome, Dylan
email me dbg2950@hotmail.com