Several years ago, I had some leakage at the mast boot on my '87 38-200. I purchased an innertube for a small tire (my recollection is that the innertube was for a wheelbarrow) and then cut the innertube so that it would wrap around the mast a couple times. I used some sort of sealant at the top portion of the innertube and, of course, used large metal hose clamps at the top and bottom of the innertube. And then I wrapped the "mast boot" with relatively wide, white mast boot tape. No leaks over the last 5 years.