Good suggestion.. I've used three different OTG cables (two of which are practically brand new/never used) and the issue still persists. I'm 99% positive it isn't the pins/contacts degrading since charging the phone with a USB cable works just fine. I've swabbed some deoxit onto the contacts anyways.
The problem with verifying using a charger and charging is that it does not require all pins to be working for it to charge, while in host mode all 5 pins are needed. Swabbing it with deoxit just doesn't cut it(scrapping is needed) if real oxidation has indeed taken place(which I doubt so but you never know).
Anyway does the connection feel loose? It might also be that some lint or dirt is inside there preventing it from having a good contact.
Anyway try this, use a toothpick, previously buffed with a fine sandpaper like the image below. You can use other objects, but with the toothpick you can do it without turning off the phone because it isn't a electrical conductor and you can also sharpen the tip very easily.
You should clean the area paint in blue below:
After this you should give special attention to areas in microusb port marked in red below(top & bottom part of the connector which is where bolts fits and attach the cable to the port. You should try to clean as much as possible dust that has entrenched there making for a loose fit.
If still persist I think it's time to get it serviced. Good luck!