Sorry, but the old adage "You get what you pay for" is sadly true in the drum pedal market... That said, maybe the angle you have the pedal at is keeping the little universal joints in a bound-up position that won't allow rotation without a lot of force? Even my
DW pedals have a point that you can't go past or they stop working correctly. So, if the left pedal is facing sharply inwards, in a tight "V" pattern it may be part of the problem...
The only other thing I can say is get a good lubricant and make sure the bearings are oiled/lubed. And no, WD-40 is NOT a lubricant like they advertise--it is for Water Displacement and cleaning, thus the "WD". WD-40 will dry into a non-lubricating residue that will actually bind some tight-tolerance machines. Tri-Flow or a similar teflon or silicone based spray lubricant is a way better option...