How to disassemble the controller.

Speedlink Wireless Gamepad StrikeNX.Sticks a little tight began to go,so I decided to disassemble and lubricate.Unscrewed the back of the case,then I do not know how to pay rent,nothing damaging.There are no latches,but the top of the controller with the inscription Speedlink(which still triggers attached),kind of like peeled off,but very tight.And it looks like it should not be.Anyway,write if you know how to solve this problem.
PS.Can I lubricate with silicone oil PMS-1000?