My 3 speed gear shifter is stuck. I want to open the cover so that I can clean the old lubricant and dust and apply new lubrication. There are no screws on the top and I am not able to open it even from the bottom. How do I open it?
Page 17 of the dealers manual shows that some of these shifters are not meant to come apart and cables are replaced with an access screw instead of removing a cover. The manual says not to disassemble further. The shifter may not be able to be easily re-assembled. That said, disassembling from the bottom would probably be the best way to open the case. It looks like there are some screws on the underside.
You may be able to remove the screw that gives access to the shifter cable and spray some W-D 40 in there to wash out old lubricant. Some spray chain lubricant into the same port once the WD-40 dries, might get it working again.
An internal piece may be broken if the lever is completely immobile. The pieces inside are intricate and do wear out with use. my 5600 series front shifter had a pawl break off and it was toast. no lubing could bring back its function. the other lever I gave the lube job i described and it has been working smoothly for another year so far.
I had the same problem on my Pinnacle Lithium bike.
I was able to remove the bottom bracket in the end but not the top. There's a little central piece that sits above a screw. You can't tell the screw is there but if you pry the black piece up it will come off and you'll see the screw.
A word of warning though, once I did get under there, it was pretty confusing and I wasn't able to put it all back together again correctly. This is partly because I suspect one piece is broken.
Anyway I think it's a bit of a cheapo and not really worth fixing.