I just inherited a grass cutter with an 18.5 ELS Model 31 on it. I’m plenty familiar with Vanguards but this is strange to me with this thing. The oil level looks correct and it runs with decent power. Sort of skippy at full rpm but with the blades running you don’t notice any stumble. I had to clean the carb out since it sat unused for 5yrs. After 20 minutes or so it will randomly bog down and just billow gray smoke for 5 seconds and then clear right out and keep going. Motor is more “clackety” than a Vtwin but I guess that’s more normal than the smoother Vtwin.