You didn't state the problems the machine is having.  Because these are full of moving mechanical and electrical parts, these can suffer from sticky / dried out oil or grease.  Parts need to be able to move freely, in order for things to work.   These machines are a marriage of electrical and mechanical parts.  Relay contacts need to be clean and correctly adjusted with adequate clearance, contact pressure and  and over-travel.  Buy a GC electronics "contact burnishing blade for cleaning up oxidized / fouled contacts.  Never use any form of sand paper on delicate electrical contacts.  The hopper also contains moving mechanical electrical components that are prone to becoming gummed up.   Check inside the top box, as there may be steppers in there - and those require service as well.  The "Jones " plugs on the mechanism, hopper, stepper must be clean and carefully aligned.  If not making good contact on all of the pins - some or all features of a game won't work.  I use 100% synthetic electric motor oil on these.  No detergents in the oil.  You can use sewing machine oil, or 3 in 1 electric motor oil in the blue bottle.  Do not use 3 In 1 in the red and black bottle, as it contains waxes that will gum up.     

These are the tubes and ballast that I just replaced in my 809 and attached is a picture of the old tubes that came out.

https://www.amazon.com/dp/B00EHK9S02?ref=ppx_yo2ov_dt_b_product_details&th=1

https://www.amazon.com/dp/B00G9BJRH6?psc=1&ref=ppx_yo2ov_dt_b_product_details

I cleared the machine and set it up..  I'm getting 5.0.91 error. Any help appreciated

It's no big deal.  Just make sure the power is off whenever connecting/disconnecting anything.  The plugs in the front will only go back on one way, so no worries. 

I'm looking for monitors for bally alpha pro 2. If you have any other type of monitor to convert, I'm also interested.