97 Coolant overflow tank pull-open cap leaking under pressure/coolant heat

[cjstew4]

Anyone replaced this pull-open cap lid to below seal assembly since mine oozes sometimes due to age/heat etc and gives you that awful "I must have another coolant leak somewhere smell/worry" ? Don't tell me I have to buy the whole tank assembly to get this. Any quick-rig fixes (that can hold up to the heat/pressure) as well to improve both sealing black plastic joints (pull up cap to black plastic ring, ring to coolant tank? Thanks.