Should be alright if you haven't got balance blocks in the boom.
On mine you take the pin out that holds the sheaves at the aft end and that gives you a good chance to pull the mouse then the ropes through and then you replace the sheaves.
I had to do this last year in Yarmouth. After several failed attempts I went to the chandlers, it is a real aladins cave, they sell anything from darts flights to radars. Anyway I bought a very thin 5mtr drain rod type thingy for £2. 50 it did the job a treat.
at the clew end:
lightly tape a thin line to one of the other reefing lines on your boom
leave a loop at the foreward end, past the tape
pull the loop from the clew to the tack end
go fishing with a thin bit of wire at the tack
sounds mad ? worked for me twice !