I read somewhere it could be a solenoid valve,is that true and could I do it myself?

Have a 330xi 2003 was thinking of flushing and changing the transmission fluid/filter,has 150000 miles and when it's cold it doesn't connect into drive from reverse right away,I read somewhere it could be a solenoid valve,is that true and could I do it myself?

__________________
This post was auto-generated based upon a question asked on our tech article page here:

[Nick at Pelican Parts]

There are several solenoid valves in the valve body and you are going to have to be able to determine which one is the reverse solenoid of the group

- Nick