Manitowoc 2900T

Anyone here have any experience running a Manitowoc 2900T? My employer bought one a short time ago and an issue arose with it the other day. I was lifting a 54000 lb load when the boom suddenly ran wild. Applying the auxiliary boom brake held it while I swung the crane and put the load down. Our mechanic ( nor anyone else on site ) is really familiar with this unit. We run an American 5299, Linkbelt 98, 108, and 418, as well as various boom trucks and a Maeda juicer. Occasionally the 98's boom will act similar if it has been raining a lot and it hasn't been used for awhile, as the frictions get wet ( we keep one hand on the boom dog until we dry them out ), but that isn't the issue for the 2900T. Any 2900T operators have any advice ? Thanks, Rick

Manitowoc 2900T