I suggest leaving the tracks for a while and concentrate on the rest. It will be easier to tackle the tracks when the rest is finished and sitting there on your desk begging for the tracks.
Stop trying to pin the track links, it is a waste of time and effort. Glue the straight runs solid and save the energy for those few links that bend around sprocket, idler and the first and last roadwheel.
The issue with these tracks is that the end connectors are moulded solid with one track link. When the track curves around a wheel the end connectors will be at an angle with BOTH of the track links that it holds together.
Try joining two links on the sprocket and it will be rather obvious. The links that curve around wheels need to be cut apart and then rebuilt at the correct angles (this is a lot easier than trying to pin all the links). The pads of the links can be glued to the wheels and the centre and end connectors added afterwards.
The rest of the track is built up as solid more or less straight sections between the modified curving parts.
This shows a BMP-2 but the general principle is the same.
The 3E has some sort of cover/fairing/guide ring on the sprocket which hides most of the problems.
/ Robin