PIXMA G620 -- will not print any red at all

[WaldportTech]

I have a G620, been wonderful, till now. Magenta prints, but no red. Test sheet shows blank where red should be. No dots, no lines, nothing. I am not sure if the red tank is totally full or totally empty. If empty, ink is not going in, and I have tried 3 bottles of ink; no change -- no ink goes in. No blockages on bottles or on the printer "vents" that I can see. 

I have done clean, deep clean and ink flush more than once. The deep clean several times. 

No red, which makes for really weak images. 

Any clues? I'd hate to get rid of it, over what seems to be a trivial issue. There must be a solution, yes? 

-- Phil

[DerrickL]

This may help, Canon's very detailed on how to fill tanks including troubleshooting.

https://support.usa.canon.com/kb/s/article/ART179413

[WaldportTech]

Thanks. I've been through that document already. Jiggling bottles and making sure of  no obstructions... no help. 

I took one of the bottles of red that was nearly empty and drilled a hole in the bottom, and the ink went in. But now I need a new ink pad in order to do a flush... that pad sure does fill up fast. Anyway, it still won't load red in the normal fasion, which frankly appears to be impossible. But I gave up decades ago declaring anything electronics does "impossible," as it will do it anyway. 

Thanks for your suggestion.