Complex sentence: A third TXE2 was added later but everything was all replaced by a TXE4 exchange around 1977, some of the TXE2 equipment was used to provide a new TXE2 at West Mersea Island in Essex.
Split into simpler sentences: A third TXE2 was added later but everything was replaced by a TXE4 exchange around 1977. Some of the TXE2 equipment was used to provide a new TXE2 at West Mersea Island in Essex.