Does the size of the main vacuum hose from manifold to check valve matter?
The blue one in picture below
The original one melted near manifold.
It starts out as a larger size then goes to an elbow and comes out with a very tinny hose comparably.
Then when it reaches the check valve near the blower motor area it goes into another elbow and a larger size connection.

Would it matter to use a larger internal hose directly from motor connection to check valve?
Or should I reuse the smaller original hose and join together with a similar internal size hose?

What reason do you suppose they used a smaller size hose in between?

See picture below showing the original small hose and a larger one that I am thinking of using.
Other wise,
The clear hose would join the existing hose ends.