My rear master cylinder has a very slow leak. It requires topping off every month or so. It is wet around the seal, but no dripping when parked. It seems to leak no more on a long trip than during daily commuting or errand-running.

The quickest, and most expensive, way is to replace the cylinder.

The cheapest way is to take it apart, evaluate, and maybe just clean and reassemble. Perhaps hone the bore. But, that way is fraught with potential delays or unsuccessful results. With other bikes, I have had most respond to just a good cleanup. It it is not successful, I gotta do it over again, either replace the whole thing or put in a kit.

Does anyone have any experience that can help me guess which way to go?