Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 348Get this manual
AutoBlend Disassembly and Assembly Warning Horn Removal
1Push in tabs (a) on both sides of cover (b) and remove cover (b)
3Remove two bolts (a) and washer (b) from horn (c) using an 8mm wrench
NOTE: a-rings must be replaced if they show signs of deterioration such as cuts, swelling or discoloration4Remove horn (a) and two o-rings (b) from horn mounting postsThen remove bracket (c) from horn connector (d) 2Use needle nose pliers to unplug 2-pin connector (a) from tank receptacle (b)