Mercury 50hp unknown year and starting problems

Hi, could any one tell me the model year of my 50hp mercury serial number 9522640 from the UK?

Also, I tried taking it out this evening and it just wouldn't start, despite being freshly back from a service. There's been so many problems with this engine over the years, I'd say its started only about 50% of the time we've got it out in the water. It gets used very little as spare time or weather have rarely been good but it gets serviced every year and I just wondered what I might be doing wrong.

After trying to get it to start for a good 10 minutes tilted fully in the water the battery had died so is that the likely culprit? The starter was turning over fine until after many prolonged tries though.

Thanks in advance for any help

That is a 1988 built by Merc/Belgium.

What service did you just have done?

The battery probably died as a result of it not starting - so what I'm saying is it's not starting for some reason other than the battery.

Not getting gas or loss of spark would be the top two contenders.

Since it's not used much it could be a clogged carb - that's why I'm asking what service was done...

They didn't tell me everything they did in the service but did mention the carb was cleaned out. Serious boat engine novice I'm afraid.

Anyway its going back to the shop tomorrow so we'll see.

Thanks for your help.