Tech Info on this site tells basics for your WG7.
I would suggest at a minimum you check the following before use
Carburetor float...may be deteriorated or fuel soaked.
Gear case for evidence of water intrusion or rust
Water pump impeller
Ignition points and wiring
An old outboard motor is seldom worn out. It may have been put away due to
need for a repair or part replacement or it may just have been put away for
a next season that never came about.
Due to reluctance of dealer mechanic to work on older outboard motors you
will have to do the work yourself. Storage is almost as hard on an outboard
as being used. Mice, cold, wet, heat and time may cause problems. Bringing
an old long stored outboard back into use requires knowledge, time, effort
and possibly tracking down some No Longer Available parts.
Water pump impeller is just ahead of propeller behind a LEFT HAND THREADED
COVER...you need to remove cover to look at impeller...sometimes easy and
sometimes not so easy.
The WG7 is a pretty strong running motor 10hp was a real conservative rating probably more like 14 or so. The lower units on that age Wizard and Mercury motors used grease. I use the lubriplate 105 others use John Deere corn head grease. Squeeze the tube in the lower hole until it comes out the vent. Clean the points well and adjust them check coils at lot of them are crumbling due to age, pull the carb float out and replace or coat with fuel proof model air plane dope. (clean the tank well even if it looks clean, i did not the first time and wound up with a mess in carb.) Pull the prop and remove the cover behind it and replace the impeller ( cover has left hand threads so turns opposite of what you expect) they usually stay bent or crumble not worth the risk of burning up a motor. Any questions just ask. I have two WG7s and a Mercury KE7. Wizard ignition is easier to work on.