I would try this.
Pull Ody off the GGTS and try to draw
through it. Is it to tight? If yes then the problem is in the ody if no then the problem is in the ggts.
If the problem is in the ggts try to completely remove the draw controll ring if it is still tight I would build it with the 510 connector and try to connect it dirrectly without the over flow
tank. If it is still tight then the problem is in the ggts connector and I am not sure what can be done there. If it is ok then the problem is in the collector
tank holes and you may try enlarging them.
If the problem is in the ody try running a thick needle through the posative pin to make sure nothing is in there. If it is still to tight of a draw then you could try a new posative pin but I am not sure ho much that will help.