That’s usually a good place to start when troubleshooting a fuse blowing intermittently. GAL specifies 4 amp slow blow for 230v operators and 8 amp slow blow for 115v operators. But they also say 8 amp max for 230v and 12 amp max for 115v so you might try going to the max size for troubleshooting purposes. If it still blows you are probably looking for a short rather than an overcurrent from belt tension, door weights or parameters.