Haven't had the jams or equipment failures. However, we don't really like pellet heat and consider it a major mistake. I have sat five feet away from the pellet stove and been chilled by the draft. We heat primarily with wood, the pellet stove is only used for mild nights when its too warm for the wood stove.
Harman may have a good reputation but their Advance stove is a major bear to clean. Needs disassembly and very difficult to get to . I know one guy who sold his Harman Advance and bought a different Harman that was easier to clean.
Another problem with Harman is that you are stuck with your dealer. Our dealer did a poor installation (ignored the Harman instructions) and will not come back for warranty issues. Harman's only response was "call the dealer". Harman has protected sales territory and there are no other dealers around.
Another issue is that pellet quality has declined and prices have gone up. It's hard to find good quality pellets.
If we were doing it over again, I would not buy a pellet stove. An unvented gas (propane) stove is more efficient and much better in our experience (we had one in a different house and my son currently heats with an unvented propane fireplace.)