Slave cylinder, maybe more?

[TotalNewb]

Greetings,

I purchased a 1999 Boxster a few months, but have been having a consistent issue.

Car history is largely unknown so I am assuming the worst and working to address any issues we find or known concerns. It is a rust free California based (formerly) car and is in generally good condition with 130k miles.

My issue is that the slave cylinder has blown 3 times in the past <200 miles. Obviously,

1) I have found two straight "bad" slave cylinders (not terribly likely)
2) I was doing something incorrectly installing them
3) Something else is also an issue or is causing the failure of the slaves

The "original to me" slave cylinder broke in less than 100 miles after we obtained the car. It popped after starting from a light in first gear. Car was warm and clutch went to the floor and stayed.

The second slave cylinder broke in a similar manner when starting the car after one trip of about 20 miles.

The third broke after an even shorter trip from a mechanic who changed the cylinder, again when starting the car.

General observations are limited since the car is new to me, but the clutch seems a bit heavier than I would expect, but seemed to run smooth. The clutch pressure decreased a bit with both of the new slave cylinders, but only slightly.

I am unsure what other information may be helpful, but can offer any responses possible with the limited experience with this particular car.

Please let me know if anything else may be the issue.

Thank you.