I have a Briggs and Stratton engine attached to a Victa lawnmower with the following specs:

Model = 92908
Type = 5175 01
Code = 82072308
Horsepower = 3.5
CC = 148CC

My mower has not been starting for quite a long time. I got it from a friend and it would not start, I cleaned it and it started but was very unstable, then after a while it had no spark anymore, so I replaced the spark plug and magneto and it started. I took it to mow the lawn I mowed about half the lawn and then it ran out of petrol. I refilled it and then it would not cut the grass without stalling. Then after that I tried to tip the lawn mower on it side to get petrol in the carb, but then oil came out of the air intake and went in the cylinder and it still does not start, but has spark.

Also I am trying to replace the carb diaphragm but I cannot get the spring into the seat on the diaphragm.

Another thing to note is that most of the screws on the mower are stripped, the thread holding the tank to the mower, the thread holding the pull start to the mower and the bolt holding the auto choke cover on.

It is a complete mess, can someone help me?

Thank you in advance.