Having owned and shot more than 40,000 shots with my  JG G36C I came to appreciate this gun. Here's what I think about what one should do to  keep it in good working order and improve it. I won't be going into the goods or bads of it neither give extensive guides about how to take it apart and back, but rather give some useful advice based on the discovery of its little secrets, you can find extensive guides for this gun elsewhere.

So, let's go:

1. The gearbox is well built, has CA gears in it and will last for very long unless you are unlucky and get a defective one. However, if for any reason you need to open it, here's some advice:

• Some screws are not compatible with the Marui ones. So, if you plan on replacing the gearbox shell make sure you have the correct screws available.
• If you need to change any of: Spring, Cylinder or Piston, you should change them as a set, all together. Their sizes of the stock pieces are not exactly the same as with Tokyo Marui and many problems may occur. For example, the stock spring is wider than other AEG srpings so if you install an aftermarket piston, when the spring compresses and becomes even wider it interferes with the piston inner diameter and produces problematic functioning or stucks completely. Also, the Cylinder is wider than other brands creating sealing problems if a different piston head is used.
• After 30,000 shots the bushings were worn out and had to be replaced by metal ones. Do this the first time you need to open the gearbox even if they aren't worn yet, you'll save yourself the trouble of needing to re-open it for damaged bushings, which could also cause damage to the gears.
• Watch out for replacement motors! Some short type do not have the exact size needed and may cause the pinion gear to strip. The G&P High Speed short motor I had installed only fired 5000 shots before getting completely stripped, and this was not due to improper adjusting. In fact the motor body was so large that no adjustment was possible whatsoever. EG1000S seems to be fine though but beware it won't give you any notable performance gain.
  
• Don't use silicone or especially teflon grease in the cylinder or piston compartment as this greatly reduces RoF. Use a white lithium one instead and save the former for the gear compartment.
  

2. The screws of this gun are made of low quality metal and you need to be very careful not to strip them The barrel assembly screws and the magazine well screw are the most suspicious for stripping so tighten only as much as needed for not allowing them to unscrew themselves during play.

3. There is a standard problem with this gun, all three JG G36Cs in my team suffered from it: The plastic piece that holds the hop-up/inner barrel assembly into the outer barrel assembly breaks exactly where the pins of the hop-up unit lock themselves into after inserting and twisting. Seems like the spring inserted there is too hard and the plastic just can take its pressure. This can be repaired by using some epoxy putty to hold in place the broken pieces or filling in the space if they have been lost. Cutting the spring to lower the pressure also surely works and is highly recommended for new/undamaged guns so as to avoid this problem altogether.

4. The battery compartment of this gun is very good. In stock form it can take 8.4V and 9.6V mini batteries without any modifications (the 9.6V needs a little bit pushing though). If you want to go one step further, and want to install a 10.8V mini without spending any money on large handguard do the following: cut the plastic piece that separates the battery from the barrel/gearbox cable connector. Also, cut the two plastic pieces that protrude below the outer barrel exactly behind the flash hider (you should see that those two pieces prevent the battery from touching the outer barrel in the front side). A 10.8V mini battery now fits effortlessy in the handguard without problems. Be sure to short-circuit the fuse though as it won't stand the 10.8V (or even the 9.6V if it proves to be "touchy")

5. If for some reason your gun's accuracy drops, firstly clean the barrel thoroughly, re-adjust the hop-up and try again. If this doesn't do any good then you need to replace the hop-up bucking. This is true for all airsoft guns, I just felt it should be stated.

6. If you need a second or third hi-cap, I suggest a Tokyo Marui which is very high quality, fully winded shoots more than 200 BB's and has the added benefit of allowing you to see how many BBs are left inside.

7. After about 10,000 shots you should get the gearbox out and lube it. If you don't want to open the gearbox then there are plenty of holes in it for you to use a syringe and insert grease. good lubing is essential for the wellfare of the gearbox.

Well, that's it as far as the peculiarities of this gun goes, up till now it has served me well and although it's considered a low quality China-made AEG, it is in fact a gun that can see you through numerous battles and help you prove yourself victorious with its robustness, compactness and very good close range iron sights.