Hello!
Just started up the mower this morning (Stiga, Briggs&Stratton 625 series) and hear a strange noise coming from the engine (I'll link a video). We bought the mower maybe a month back.
I have absolutely no knowledge of lawn mowers other than it works similar to a car engine. In case you cant see the video, it's a rough and hmm, brutal sound and appears every 5 seconds or so.
Video:
https://vid.me/S05T
/Hampus, Sweden