does the machine have a lube oil system on it?if the grease fittings are under the way covers i doubt they are being used,my machine doesnt have the oil lude system and needs to be greased once a week or twice if you run it alot,but my fittings are all easy to acess without removing any covers,standard lithium grease is what i use,i hope you havnt run it for too long without lube,check your manual,good luck