If your chain was replaced a long time ago, you may need a new chain again, also maybe a new cassette. Check for wear. Your Gear hanger may also be a little out of alignment but it sounds more like wear.
Check chain for wear (using a chain ware guide tool), replace parts as needed. May as well replace cables at the same time, degrease the remaining drive chain, check hanger alignment or take it to a shop to check alignment as it can be hard to do so without the proper tool.
If your chain was replaced a long time ago, you may need a new chain again, also maybe a new cassette. Check for wear. Your Gear hanger may also be a little out of alignment but it sounds more like wear.
Check chain for wear (using a chain ware guide tool), replace parts as needed. May as well replace cables at the same time, degrease the remaining drive chain, check hanger alignment or take it to a shop to check alignment as it can be hard to do so without the proper tool.