I am working on my Bolens Kohler Magnum M20 engine. My Kohler is the early version and there appears to be a scarcity of engine parts. Does anybody know of any available OEM valves (45-degree)? The exhaust valve stems/guides have too much play and the valve stems spec at bare OD minimum. The valve guides more than likely should be replaced, too, which brings up this question: since the exhaust valve is made to withstand extreme heat, are the valve guides different too or are they interchangeable? Regards, Bojer