Let the system run for a while if the water has bubbles in it or is cloudy. It's air in the osmosis system and will go away after a while.
Replace the membrane cartridge, flow control, screen, pre-filter and post-filter if there's a chlorine taste, or odor present -- the filter isn't removing the chlorine anymore. Clean your hands and then turn off any ice maker, and the water supply into the GE system. Drain the system by opening a faucet that's down-line from the system and then turn that faucet off.
Remove the sumps -- they'll be full of water, so be careful. Discard the filters and wash the sumps with soapy water and then rinse. Remove the cap from the RO cartridge housing and remove the cartridge and discard it. Wipe the inside of the housing and cap with the towels, rinse, add the new cartridge and put the cap back on. Then install the empty post-filter sump.
Fill the pre-filter sump with water to within an inch of the O-ring and add 2 oz. of bleach. Install the sump. Turn on the water supply and allow the system to fill for a minute. Open a faucet and allow it to flow for 10 minutes. Close the faucet for a minute and repeat until the bleach odor has dissipated.
Remove the sumps, insert the filter and lubricate the O-rings with silicone grease. Then tighten the sumps. Do the same with the RO cartridge O-ring.
Replace the flow control and screen by unscrewing the black ¼-inch line from the fitting
and removing the flow control with a knife edge. Remove the screen with the toothpick, replace it and tighten the nut. Allow the system to fill.