Mate it's a piece of pie depending how easy it is to remove the top link, i recently undertook the job on my 50 etec and the top bar was seized in, took a good deal of heat, oxy, and inox then thumping it with gimpy and brass dolly to get it out, probably 4-5 hours, heat it up quench it with inox then smack crap out of it a few times then repeat,p. You may or may not have the same trouble. The rest of it is wiring which is quite simple.

 Yeah there should be a locking tab when motors tilted almost all the way up, otherwise you can chock it with some wood. I'd hate to see the bill if I had a mechanic do it, a good slide hammer kit would have helped too but you may not have the same trouble I did, I know the yamahas are pretty easy not sure of your model.

 I had one replaced recently,(60hp merc 2-s) it was in for a service, trim motor was dodgy, had a good s/h unit avilable, easy change over if nothing is seized.

 I won't say where - but I just got told its a day's work - $1000 for labour and $1000 for the part.... 'Motor's gotta come off....'

If you buy the SELOC Yamaha, Mercury & Mariner servicing book, then you can do it yourself.
The book covers all Yamaha Mercury and Mariner 2.5 to 225 HP 1-4 cylinder and V6 4 stroke models from 1995 to 2004.

Far cheaper than $1K plus and it's very easy to follow, after not being satisfied with the quality of servicing I was getting on my Yamaha I now do all my servicing except for electronics and I don't do them because of the gear required. I got my copy from a tech book shop in Murray street just east of the Williams street intersection cost was in the region of $30.00 if memory serves me right.

Just a thought.

 The motor component would only be a couple of hundy max off ebay .. a whole new kit with ram etc would be a grandish .

I had to replace one for a 50hp mariner a few years back waited until a 2nd hand refurbed one became available from the states  can’t remember the mob . It was like $600 took us non mechanic types maybe a couple of hours to swap over .

Replaced my one on 150 Yamaha 4stroke. Dont need to remove your outboard to do this. You can test for a fault by hard wiring connections to a battery first. Worth checking B4 you spend the dollars. Might be the solenoid not the hydraulic motor? I found a new motor on ebay for $180. Still works fine one year on. Was $700 for a genuine part. Might need a few ppl to lift leg when hydraulics are disconnected to put lift lock pin/ tab in place. Or a hydraulic eng lift if you are on your own. Unbolt, rewire and reprime hydraulic fluid-Tilt up and down until all air is out. Waiting 10 mins between each few lifts will allow more time for air to rise to the resivour. Oh, and don't lift too high. If your eng gets stuck in lift position, there should be a billed screw on the side of mounting bracket. This will allow engine to lower. 

Hope this helps. 

Brett

Thanks Guys - a lot of useful info.

Its a late 80's 90Hp Mercury.

I think I will be doing it at home - haven't worked on boats but done plenty on cars - can't be that much harder or different

i did mine on a 1990 75hp mercury.it was either take the motor off the boat or remove the steering cable and unbolt one side of the motor to transom mounting bracket and remove it as there is screws in behind the plate that you can`t get to otherwise,

 Dunks post, he might part out the motor trim unit. fishwrecked.com/forum/shed-clean-out-complete-outboard-bits    if it is the same , could be. You can see it in one of the pictures. Hell, he's selling the entire outboard and two props for $200