Hello, my Hobart AE200 seeps oil from the front panel. How do I top it up? How often does the oil need replacing and with what type of oil? Thanks

It's not oil in the A200, it's #2 weight grease. Although when it gets old enough it can break down far enough to basically become oil (either that or someone put oil in it previously). There are a number of answers written on fixya.com explaining how to disassemble the transmission and change the grease. Fill with 36 ounces #2 grease. FYI : disassembling the transmission and changing the grease is a very messy task and one can VERY easily reassemble the transmission incorrectly, so consider bringing the mixer to Hobart to have the job done.