Sometimes the best way to learn is to screw up. That's the exact same way I learnt that in stats when you're graphing things the independent variable ALWAYS goes on the X axis.
Anyways.... I guess you could just play with it until it breaks. The thing is that breakage is seemingly random so you could potentially get a "cherry" and it'll last for over 9,000 rounds but the lemon rate for guns like that is significantly higher and you might be lucky to get more than 100 rounds out of it (or it could be broken out of the box or last 500 rounds).
That said, IMO it's not worth it to replace the internals in that gun and it's probably better off as a parts gun rather than fixing things up.
As for the spring downgrade, remember FPS limits are just that LIMITS not a goal. It also puts less stress/strain on the internals which should slightly help with making it last longer. As well not all chronos read the same and there can be variance from +/- 30 FPS if using a cheap chrono (worst case, just look at some of the videos on youtube about some chronos from the same company that are the same model have variance of 15 FPS) or +/- 5 FPS if using a good chrono. That downgrade will also ensure that if the chrono is reading things 30 FPS high then you should be safe.
EDIT: Check this video from AirsoftGI out, they compare a Madbull Chrono against a "prochrono" (used in real steel apparently): YouTube - Airsoft GI - G700 and Madbull Chrono Test
Also note that FPS doesn't really matter in the grand scheme of things. It will increase your total range but effective range (where you can guarantee that you will be relatively accurate) is moreso a matter of hop up bucking/unit, inner barrel, and consistent compression from your piston/cylinder. Also, using .25g BB's when playing outside is also recommended, it will lower your FPS and total range but effective range is increased due to it being less affected from cross wind (remember, the concept of momentum from Science 10 or Physics 11 where heavier objects require more force to change it's vector).
PS: Go to PoCo Military, they'll get you sorted out.