Why is my fountain pen skipping?

In order of likelihood: factory oils on a brand-new nib (flush with a drop of dish soap in water), misaligned tines (check with a loupe — one tine higher than the other), a too-steep or rotated grip missing the tipping’s sweet spot, or a dry ink/nib pairing starving the flow.

Work that list top to bottom and you will fix the large majority of skipping pens at your desk in an evening, no tools beyond a glass of water and your thumbnail.