To confuse things, the Dictionary of Newfoundland English has a totally different definition:

muckle v To tug or strenuously pull up (something).
1924 ENGLAND 237 Here I been workin' ahl me life, draggin' and 'aulin, mucklin' up
grayples. 1975 RUSSELL 20 'Did you get 'em all dug up?' said I. 'Yes, Paddy,' said she,
'every blessed one of 'em, exceptin' one ... one of 'em was a bit too big for me to muckle.
So I left it bide for you and the crew to handle.'

I've been away for a bit so it's taking me a while to get back into the swing of things. Thought I would make a first post using mostly someone else's words!