to my knowledge they ain't no such thing as a gs2100. I asked if you had a GR2100 or what, and you said yes. Then said "yes I have a gs2100". Don't make no sense.
i can assume it's a gr2100. R not S?
if so you would've been WISE to have researched it and sold it while it was working to buy something that is more reliable and actually works when you want it to, and doesn't cost an arm and a leg to fix
anyway, gr2100 has a clutch for the blades, which is internal to the transmission. It often fails. Kubota makes a kit to "fix" it, but you gotta take the transmission out to do it. Well you don't "have" to take it out but it's a whole lot easier to do so rather than laying on your back trying to line everything up because if you don't get it lined up you WILL crack the case or the cover (often both) and at that point you're gonna have to buy a new one and then you're gonna have to pull it out anyway. The pto clutch kit isn't exactly cheap either, or wasn't the last time I put one in.
I do not have much love for the GR series mowers if you can't tell.
but with all that said I don't know what a GS2100 is never heard of it, nothing on a google search, is it a gray market or is it a EU or Aus market?