I use several 306s, having to hold the tail thread is standard, if you let the presser foot catch it, then the motor sometimes can't even start there is so much tension unless you give it a hand start. I like the idea above, "needle down, foot down, sew"
The clackety clack is either the hook, or the feed dogs. Make sure to give the lip between the two revolving parts of the hook a single drop of oil. While underneath, give the large, knurled hand screw a tighten with a screwdriver. Don't force it, it might not even seem like it moved. That often clears feed dog noise, as it is the adjustment screw. The lock screw for that large one is never touched in this procedure, somehow the large one seems to be able to back out ever so slightly, even with a lock screw.