Our fire place would only run for a short time and then shut off. There are 4 screws all toed into each corner of the fireplace. We have a 2013 36rl Redwood. That allows you to remove the fireplace from the box.
We took ours out and opened up the top where the squirrel cage is located and the fins of the heating unit. We first vacuumed it but found that only helped for a short period. The fix was buying a can of pressurized air like you would use for your computer. We sprayed it out really good., got all of the dust out of it. We hooked it up put it back in the box and have not had anymore problems.
I hope this works for you, if it is the same fireplace. Note: we had to buy a longer shafted Phillips to get to the screws.