Is a thermal release valve easy to replace on power washer pump?

I have a Troy BIlt power washer with Briggs Stratton engine. I ahve a leak in pump. Appears to be a gasket or could be thermal release valve. What's level of difficulty in replacement?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0