trularin,,,,, a small nut dwon the carb? I've seen them pass on through, depends on the size, and youe budget.
Debris in the motor? Depends on the size and your budget. Are you feeling "lucky", 'cause sometimes you might be!
Sometime it comes down to a couple of choices when your on a budget. When you don't have the dollars sometimes you gotta take a chance, and sometimes "life sucks".
1. Risk doing the rebuild yourself, that could be as risky or more so than doing a flush! Only the owner can make that call.
2. Take it somewhere and have the motor rebuilt, on a tight budget option #2 simply is not an option!
Faced with this very problem myself recently I went with option number 1. But when I was a young man, the first couple of times I went with "option #1" resulted in toasted motors anyway!