Mine is all original other than a connector or two I replaced on the GI.

Once I went to all LED though, the draw on those connectors is much less.

Another thing I did was remove the battery holder and install a remote one in the back box. Always do this. To all your games. Unless NIB obviously.

Other than that, my T2 is original everything else.

T2 club is a better place for this question fyi.

There are some things you can look for now and replace, but most I'd just wait until you experience an issue.

GI connectors and headers J120, J121 and J115. Check for burned connectors/headers and replace now.
Replace the batteries with a remote holder or add NVRAM or go to Lithium batteries to prevent leaking on the CPU. Do that now.
Resets. I'd just wait and address these if it start happening. J101, J102, J114, BR2, C4, C5 and possibly +5V voltage regulator.
DMD HV section. Again I'd just wait, but look at the bottom 1/3 of that board and see if it looks toasty. If the DMD starts acting wonky, $5 in parts and some time and you can rebuild that area.

Off the top of my head that's all I've ever experienced as common issues. The rest of the stuff that can happen would be fairly rare unless you did something stupid like work on the game with the power on.

I wouldn't touch anything if I were you; you can cause more of these headaches screwing around with stuff then just leaving it alone.

Agree with the others if it is working fine leave it alone. It really will not get much of a workout in a home environment.

The only thing you should really do is get the batteries off the boards or replace them if you haven't already.

I would not replace any boards since it is working.
I only suggest upgrading to NVRAM on the MPU to remove the batteries for good.

and J210 in this order.

Good alternative if you don't go with NVRAM.