As discussed in earlier BC threads such as:

Common in many of today's modern rackets with more than 72 holes/grommets (Yonex's Voltric and Victor's Meteor series), a stringer will encounter instances where the main strings will cover/block a cross grommet. Awls and string mover tools are common approaches to unblock and open up the cross grommet when weaving.

Another tool to consider is to use loose scrap string (about 6 inches).

1) Thread the scrap string between the two main grommets such that it is perpendicular and held to the frame by the main string. It is easier to do this prior to applying tension to the main.

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2) When it comes time to weave the cross string into the blocked cross grommet, simply pull gently on both ends of the scrap string up/down to uncover the cross grommet.

3) You can now then thread the string through!

Below is a video illustrating this: