Unfortunately yes. And bench bleeding a new line is not really fun but seems to be the only way to really bleed all the air out before bleeding the slave cylinder. Also there should not be threads as the plastic line is pressed onto the bottom of the reservoir. If you can get it fixed before the reservoir goes empty then you should be okay as any air should in theory rise to the top of the reservoir if it has not already been introduced into the master cylinder. FYI the reservoirs on the BIIs and 91-94 Explorers are the same if you need one from the JY. However, that plastic line does not play well with heat or other forms of persuasion....