Marvin, (Topeka, KS)
Marvin, it appears you either have a mechanical or possibly a hydraulic problem since the levelers extend as they should some of the time. Or both! Look closely for a pinched hose, a damaged mounting bracket or any binding of the movement throughout the travel of each jack in question. It is also wise to lubricate all the moving pivot points with white lithium grease. There may be a filter in the hydraulic system for those jacks so check to be sure it is not partially clogged. Follow each line from the reservoir to each jack and inspect closely for leaks or kinks. Aside from the mechanical, you may also have fouled fluid in the reservoir. At eight years old, it may be time for fresh fluid!