Pinball maintenece schedule

[Steevsee]

I was working under the PF of my Boobwatch...ah, i mean Babewatch...er, ah, I mean  BAYWATCH... today when I noticed my subway ramp had started to crack at one end. 
I had repaired this awhile back and kept meaning to check it but only did it today while I was cleaning the optos in the ball trough (which started playing up today).
So far I usually just fix (or try to fix ) things as they happen but also sometimes I need to order parts or just plain don't have the time.
This can leave a machine not working properly for awhile, so I thought I would try to create a bit of a maintenence schedule for pinball machines to keep them running at their best.

Just wondered what everybody else does and how often? 

Do you replace a blown bulb immeadiately or do you wait till you need to go under the bonnet for something else?
Do you change your batteries regularly?
How often should I check board connectors, or just wait till something goes wriong?
Would it be worthwhile checking coil resistances once a year? maybe?

I've come up with a few things to do (not too sure on my time frames though). Please feel free to add anything else and also comment on time frames.
I guess some things would depend on how much the machine was played and other things would be done at regular time intervals.? 
Also any special maintenece items for EM machines?

1. Change batteries (yearly)
2. Clean and polish playfield (monthly)
3. Ball change (? yearly)
4. Clean exterior cabinet (monthly)
5. Under playfield inspection (every 3-6 months)
6. inspect all connectors and boards (yearly)
7.?
8.?

[Strangeways]

Batteries - Very important. A new set of batteries is far less cheaper than a new CPU board. Change yearly.
Clean and polish playfield - Depends of how much the game is played. At least once a year.
Ball change - I examine my balls and I usually throw them in the tumbler before discarding them. If they ae still godd, I use them again - in the same machine.
Machine cabinet clean - Mr Sheen once a year and windex on the playfield

Usually, a fault would occur somewhere along the line, and while the playfield is up, I check everything looks ok.

DMDs - When powering on the machine, any errors are reported - so you attend to them as they occur.

EMs - Occasionally check contacts around the playfield and inspect the stepper units

[studley67]

with 25 machines,if i did all that i would not have any drinking time.lol

[studley67]

. i love the bouncing action in the match mode.

[Steevsee]

. i love the bouncing action in the match mode.

Definately a nice feature (or nice pair of features)