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Good eye. I fixed your pics. Next time click insert all before you post. 
Put oil on it then press it in being sure it's not in too deep after taking out the old housing of course.   
Steve

That one piece tach drive housing was real prone to develop oil leaks over time. Kawasaki over the years updated the tach drive housing to a design that was not locked into a fixed position. The kickstart Kz900 / Kz1000 motors used two different styles of how they held the tach drive housing in place. Kawasaki did release a service bulletin on this update. 
Any one of these two updated tach drive housings and their mounting hardware will almost eliminate any chance of developing an oil leak from the tach drive housing. These updated parts should fit the Z1's and Kz900 motors too!!!! If I was rebuilding a Z1 or a Kz900, I would for sure go to any one of these new style tach drive housing and their mounting plates.
I HATE ANY TYPE OF OIL LEAKS ON MY MOTORS!!!!

Updated style tach drive housing and mounting plates installed on cylinder head.
 

The most common Kawasaki replacement tach drive housing and mounting plates.
 

The other updated Kawasaki replacement tach drive housing and its mounting plate.
 

Correct. I didn't realise the rubber seal had metal inside it. Took a while to router out the remaiing seal. Thanks for that.