Problem with CENTER button



I have recently been having a problem with using the Center softkey on my RDP-149. When I am returning home from a trip offshore I like to run the display in Overlay mode with the autopilot on. While I am running if I use the trackball to move the cursor for any reason and hit Center softkey when I am done it moves the screen back to center like it should, but then the Center softkey keeps coming back on. I keep driving off the screen and it beeps. I keep hitting Center but it comes right back up and the cursor stays on the screen and I run off the screen again. I keep hitting center and every time it returns the screen back to center but will not stay there. To remedy this I keep hitting center then quickly hit another softkey and sometimes it makes the center button not come back. I hit so many buttons so many times I have no idea which time made it work. After I get it to finally go off it will be fine as long as I don't touch anything. What am I doing wrong? I don't remember having this issue until last year and this system is seven years old. Thanks-Rick
The center softkey appears when the trackball moves which puts the unit into a cursor mode. One way to see this is to press the nav off softkey once to display your position across the top of the screen. When there is a big black dot next to the lat/long, the lat/long is the current location. When there is a + next to the lat/long, the lat/long is that of wherever the cursor is. When you press the center softkey, look for those indications and see if the dot changes to a + when the 3rd softkey changed from nav pos to center. If it does, then it's not a button problem, but rather a cursor drift problem due to vibration and a worn trackball assy. Normally that means the trackball assy needs to be either cleaned or replaced.