Hobart N50 gear noise

Hi all,

I've picked up what I believe to be a reasonably new Hobart N50 off ebay UK.  It's got a sticker on the bottom (not a plate on the back) and appears to be from around 2014 or so.  It was used in a catering college apparently, very few marks on it, grease on the shifter (after taking the plate off) looks clean.

Seemed to run quietly in all three speeds when cold but after running it for 10 minutes or so the motor area felt 'vaguely warm' (not much more than body temp) and 1st gear has started making a noise.  2nd seems pretty quiet.  3rd seems quiet but the machine sort of throbs every few seconds which you can hopefully hear in the video.  I can feel the 'throb' as a slight vibration towards the motor housing.  There is a dent on the control panel from one of the switch guards being impacted.  No idea if this has affected anything else but the machine looks in great shape externally otherwise.

Wondering if I should just send it back as I have 30 days to return it (reluctant to it was a good deal for a newish Hobart mixer in the UK) or whether some more grease would fix it.

The video of all 3 speeds: https://youtu.be/6OI1InPrI2w

Edit: I tried mixing some dough in it (ie: putting it under load) in 1st speed.  Seems quieter.  Wondering if the planetary needs greasing as it was missing the taper pin when it arrived and there wasn't a lot of grease on there: https://youtu.be/R6TBaLy_yzg

Edit 2: Maybe I'm talking cobblers about the planetary - thinking it if was that then all 3 speeds would make a noise :|

Edit 3: Took the switch plate off and looked inside - seems to be a strange lack of grease - others report it being 'packed full' - mine certainly isn't.  Tried to take a couple of photos - see https://imgur.com/a/JtdUiCP

Really hoping it's a 'fire a load of grease in there' job and not a 'send it back' one :|

Many thanks for any thoughts or advice,