The 170 has the Kawasaki FC420v, 14hp engine. For a couple years now the starter will click from 1 to several times before it engages. There's seems to be no pattern. Any time, hot or cold, it may engage on the first try or the 50th. Recently, it's been getting worse. I was doing some other work on the machine and knowing the starter was over 20 years old, I purchased a new starter with solenoid and installed. It didn't solve the problem... still doing same thing. Any ideas.

Hi,
You need a Low Voltage Kit, part #AM107421. You may well need new battery cables or ends on them, if the copper wire has turned whitish or bluish or somewhere in between.
Peace,
Clarke
PS Beats the $300+ for a new starter, at least for a while, if not permanently.