Error code P0731

Nissan Micra K12 1.4 2004 with automatic transmission. Around 115000km.

Received that error last summer after long drive on a hot day. Few times before error there have been short issues during driving that it feels like its car is not changing gear and for that speed is limited. Always after short while it picks up again and all is good. Cleared error and after few nights continued my journey without any problems. Had transmission flushed and oil changed after that. All been good thru autumn, winter and this spring. Summer is coming and hotter days ahead which makes me worry.

Im trying to find out what kind of operation it is to change shift solenoids. I know i do not own skills nor tools to do it but to get idea what im facing if it comes to that. Does it require lots of work or can one with proper tools and experience do it in reasonable time without me spending tons of money to get em changed ? :)