Totally agree, turning it down is just awkward for no reason. I had a mechanic offer me a soda once while he looked at my car, and we chatted about the game that was on his radio. Later he threw in a wiper blade for free, just because. That five minute chat made it feel like we were on the same team, not a transaction.

Yeah that whole 'take it slow' advice is KEY. Reminds me of when I tried to re-cable my old road bike in a rush before a group ride. Got the housing stuck in the downtube so bad I had to cut it all out and start over, missed the ride entirely. @young.beth is right about the guide wire, it's one of those things you only forget once. Sometimes the simple extra step IS the whole job.