2010 Rancher 420 Purchased/questions

Good Evening, I’m new here but had a membership years ago and remember all the help I got from shadetree and I see he’s still here which is great. I bought a 2010 Honda rancher 420. Manual shift 4wd. No digital no power steering pretty basic. Came with msa14” rims and 29.5 laws both new. Question about a few things. What are some things I can check. On site before I bought the bike I checked engine oil, rear diff, front diff oil. Rear chunk and rear driveshaft are new replaced February this year. Some things I missed over how excited I was over the bike. Front driveshaft has a pretty good seal leak and I’m having a tapping that I don’t think it’s valves I feel it’s the timing chain. I have a video of this but I’m not seeing where I can upload a video. It’s not extremely loud like one about to break but it’s loud enough. No high pitch whine upon high throttle yet either. In 2015 when I had my last rancher I did the gear reduction myself and still have that manual that covers this model if these are some things I can fix myself. Also has hmf exhaust, I 100% will have to add a Gr for this bike. The young man I bought it from said it had one but if it does it’s 18% or so and not enough. Overall the gentleman wanted 3300 for the bike and I gave him $2300 cash. Thanks everybody for the advice ahead of time and excuse the grammar errors. My career is an detective for a sheriffs office and I type enough perfection at work.