Have you try blowing through with a air line ? maybe only the inner cables goes through the middle off the top tube and outer is only at the front and the exit..my guess
I'll have a check with a torch tomorrow, but it sounds like internal stops are likely as it goes.
Or use a hair dryer or vancum cleaner
@Vinbenzo started
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Have you try blowing through with a air line ? maybe only the inner cables goes through the middle off the top tube and outer is only at the front and the exit..my guess