I used a screw driver and went around in small increments. It won't be pretty but works. During that process it is important to keep the tube from getting oval. The round shape is important to get a good seal around the O-rings. Also good to check that it can fit into the reader. A bit of extra bending is normally required to get it to fit.

Excellent guide! Thank you for putting this together. I replaced my switches following my mouse double clicking on the left button about 5% of the time. The switches I ordered didn't have the right terminals (they were flat and short with holes in them). I had to truncate them a little to make them fit into the holes in the PCB. I also replaced both left and right buttons since the switches I ordered had a minimum order quantity of 5.
Perhaps indicate part number for the switches that are the correct type in the guide? I ordered the Omron model D2F-01F-D. They work great except for having the wrong terminals. You probably want to order the model D2F-01.

Like I said, once the metal bend is pried open you can use your fingers. The top cover is not held in place by anything other than the o-ring.
To pry open the metal bend I used a screw driver.

Are you referring to the black plastic cap that protects the sensor? I use pliers and a vice if necessary. For some loggers this cap is attached very firmly and quite a bit of force is needed to get it off.
For the other side by the IR diodes you should not need any force and can be pulled off with your fingers.

I hope I understood your question. After re-assembly I just bent the metal edge back in place as good as possible which secures the head in place for normal operation.

I have not tried this with the LTC model. I suspect it would be more difficult due to the conductivity contacts which might have additional seals in place and might prevent the PCB from just sliding out once the top is removed. Should you attempt it it would be great to hear some feedback.

I was wondering the same thing.. I really like the build quality of my G413 other than the horrible Romer-G and key-caps. Would love to replace every switch with something decent even it means having to de-solder and solder in new ones one by one.