1 memory port not working on my sony vai...

The memory sockets on the GRZ and GRX series are notorious for failing. Some companies can resolder the sockets but the repair may not last. There are a number of issues these are prone to (they also seem to have more failed backlights in the LCD than other machines - Is your LCD pink when it boots up??),

Considering the age of the machine and these issues, it would be best to replace it with something else than try to patch this one up.

If this is the only troubles you have had since new, then your GRZ has already outlasted many others :)