One pixel spaces between letters

hi, how can I fix this odd white spaces between letters?
all connected letters have -10 side bearings, and in most letters there is no problem!

What are the side bearings of those letters. You need a slight overlap (20 units) to avoid problems like this.

side bearing are -10 and in most letters its fine!

Then maybe the path direction is wrong.

What is also possible is that 10 units overlap may not be enough.

Also consider disabling hinting, or at least do not hint the horizontal connectors, because the distortion caused by hinting may bring the gap back, especially in smaller pixel sizes.