I have recently been reading "The Heisler Locomotive 1891-1941" by Kline. One thing that may have impacted Heisler sales in the early period was that Charles Heisler was a mechanical design engineer/inventor, not a promoter. He sought out others to license his patents to. The Stearns Co. which built the locomotive for a while was actually partially owned by one of the principals of Baldwin Locomotive Works. Heisler eventually sold all of his rights to the locomotive design and worked for Alco for a period of years, then moving on to General Electric. At GE he was involved in design of refrigeration and heating equipment as I recall, ironically not locomotives.