I have 2 possible solutions, 1 is to get some PC7 and make sure the area is totally clean and dry, Patch it with the PC7 and it will hold up for the life of the master cyl. Only draw back would bo havinbg to pull the cover to check your level.

The other would be to get a cheap HD after market unit to get you by for now. Those tend not to last very long though.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!