HELP ME SERVICE MY BIKE

[Chaos causes]

Guys, I am planning on changing the water pump seal on my 16 390 because of the mixing issue(you might have already guessed why). The SVC guys actually ripped me off last time and in their bill,they claim to have changed the water pump rotor completely, but I got my bike back the very same day,(changing the water pump rotor requires opening up the engine a bit right? as far as I know). I called them once the coolant started disappearing(the tank is empty now) a rider whom I met had the same issue and he decided to change the seals all by himself and his bike is good to go now. Since this is my first time servicing my bike at home is there something I should look for or be aware of in specific? Any suggestion is welcome (I got the stanley 46 piece 1/4" toolkit for the purpose)
P.S. I saw threads on upgrading the water pump seals, but then I don't think I can get the EXC450 seals in my country as there is only the duke/RC 125/200/250/390s and the DUKE790 in my country. And I would like suggestions on upgrading the seals

 

[ReidMcT]

If by 'rotor' you mean the impeller, then that is a very easy job. In fact, you will be removing the impeller as part of the job to replace the seals.

In addition to an 8mm socket wrench, you will need some 'inside' snap-ring pliers and some tools such as picks and screws to pull out the old seals. And a large socket or other right-sized tool to drive the new seals in straight.

You'll probably be able to re-use the rubber seal on the pump cover.

 

[Chaos causes]

If by 'rotor' you mean the impeller, then that is a very easy job. In fact, you will be removing the impeller as part of the job to replace the seals.

In addition to an 8mm socket wrench, you will need some 'inside' snap-ring pliers and some tools such as picks and screws to pull out the old seals. And a large socket or other right-sized tools to drive the new seals in straight.

You'll probably be able to re-use the rubber seal on the pump cover.

In the service invoice, it was mentioned 'water pump rotor' and charged 10 times the price of a seal. Now they claim it is the blown head gasket that owes all this coolant drop. So how do I look for a blown head gasket and how do I diagnose for coolant leaks? Could this be coolant leaking from not so superficial somewhere? If that is the case, it is supposed to be a visible leak right?
P.S. the tool kit has sockets up to 14mm, enough to get this job done?