Power to panel in mobile home
First let's look at your situation where you have a 60A Service Disconnect and a 100A main breaker in your panel. You should never have a larger amperage breaker after a smaller trip breaker because if you have a fault downstream, the service disconnect will trip prior to your main breaker. So your main breaker is ineffective and is only being used as an equipment disconnect.

Second: Yes you can increase your service disconnect size but only if your feeder conductors to your panel are the correct size to handle the updated overcurrent protection.

Third: Your dimming may be caused by your service feeder being undersized and is causing a voltage drop to unacceptable levels or it may be caused by a broken neutral or ground. I would have that checked first before going to the expense of replacing a service.

Hope this helps and good luck.