George is correct. The 'red' insert was held fast by ancient congealed castor oil which had turned to the consistency of badly set toffee. A little heat from a pin-point propane flame spread evenly over the intake tube, a deft twist with a soft jawed 'nutcracker' shaped tool, and out it came.

Engine shown is a super little runner, though the contra is a little 'sticky' when hot. No biggie. No leakage at all, and far better than being too loose. The home made intake at 4 mm diameter worked very well.