I think,many psp users may suffer some problems about PSP1000,which was may caused by analog stick assembly dirty or messed up or lack of proper contact between the underside of the motherboard (on the lower-left side of the screen).
So,here is two ways to fix above problem :
If the issues resulted from analog stick assembly was dirty or messed up ,you can choose a Analog Stick Joystick replacement,such as : 3D Analog Stick Joystick and so on.
if it's the problem of lack of proper contact,you can try to fix it by following steps :
if you dont know whether this factor is the mainly reason,you can test it by yourself first,you can just take your faceplate off and press down on the area circled in red while moving the stick to see if this will fix it. I recommend just opening the web browser to test the stick since you can see exactly how it's reacting in there.
1. Take off your PSP's case.
2. Unhook the home bar.
3. Loosen the screen and it's metal case from the system. Some guides have you pry the screen out of it's metal case, don't do that here.
4. Place a few strips of paper where I did (the white in the same section that's circled in red on the upper pic).
5. Re-assemble. If there's dust, go to the next step. tongue.gif
6. Disassemble and clear out the dust, then go back to the previous step. tongue.gif
So when you put the PSP back together the strips of paper mean that the screen is pressing down on the motherboard more, which is pressing down on the contacts more!