Switching from base to wand suction when reclined

Switching from base to wand suction when reclined

The suction switches on it’s own from base to wand when hoover is reclined more than 45 degrees. When upright, the wand is working; when reclined by small angle it switches to the base but when reclined more than 45 degrees it turns back to the wand. I wonder what I can do to fix it?