*Looks like you don't have an enclosure, so this would be good. PLA takes longer to cool than other materials.
*Do you have a nozzle fan? This is a requirement for PLA unless it is a large print. More travel means the heat isn't sitting over any given part for a given time. This helps even with a fan.
*Even the tensioner could be to blame. Tighten it if you can, but without causing stress lines in the filament.
*Clean your gear and bearing. A couple quick blasts of compressed air will do the trick.
*Dial back your retraction a little bit, and recalibrate your extruder. Even with a clogged hotend, this can be done by cutting the filament, removing the hotend, and mechanically calibrating without the hotend attached if you have a full clog.

To clear a PLA clog, bring your extruder temp up to about 150 for a minute or so, and insert a probe. A guitar steel guitar string is recommended, but a short blast of ABS will work just fine so long as you pull it out as soon as you see a color change. If using the same color, use effective judgment on depth.
There are many inferior hotends on the market, and installed stock on several printer brands. So run through these steps, and if they don't work, I have a couple other solutions.

I have a grid mbot II and have problem with the engine that drives the filament , someone can give me a clue of the problem?

Deputy URL problem

https://goo.gl/k28Vss  thank evertone.