Riddle of the Lock (with lines from Shakespeare’s King John)

Something about, a little from the right,
In at the window or else o’er the latch,
zip-wire towards me, get the glint in sight,
sing gently through your rust: catch as can catch,
the draught to patch, the quiet, the itch to scratch.
And I am I, howe’er I was begot:
unhatch me, old friend, old forget-me-not.