HI everyone !

I noticed for a while my car seems to have lost some top end power. recently after diagnosing some front end accessory rattle I found that the timing belt tensioner was completely dead. I replaced it and now everything is quiet.

My questions are is there a possibility the timing belt may have skipped any cogs? I bought the car at 150k km and now its at 230k and don't have the history of maintenance.

How hard is it to change the timing belt and how is it possible for me to find out if the timing is correct or off?

Thanks!