http://bayareaamusements.com/
https://mad-amusements.com/order.php?ipa=1292

I believe that you're actually missing 5 parts in total:

(1) small, long wood screw
(2) small washers (one goes at the top of the screw above the metal inlane guide (the 2nd goes just above the playfield
(1) .541" length metal sleeve (goes between both of the metal inlane guides)
(1) .341" length metal sleeve (goes between the bottom metal inlane guide and the washer above the playfield

(I'll try and find the part no.'s for you when I get home)

I stand corrected, it's only a total of 4 parts and unfortunately, the service manual only lists the ball guides as assemblies (A-15616 and A-15617)

however, here's a photo of the assembly and one of the screw
(btw, you should have an identical set of these parts on the right ball guide, located underneath the whirlpool bowl)
I would use them as a guide to try and source replacements for you missing parts

(1) small, long wood screw
this is possibly a #4 x 1-15/32" length wood screw with a sleeved area

(1) small washer (it fits on the wood screw below the 2nd (shorter) metal sleeve and rests above the playfield

(1) .541" length metal sleeve (goes between both of the metal inlane guides)
(1) .343" length metal sleeve (goes between the bottom metal inlane guide and the washer above the playfield

note: the lengths of the metal sleeves are based on the lengths of the plastic spacers that separate the 2 metal ball guides and the guides from the playfield (that the 3 screws go through)

inlane_assy.jpg

screw.jpg

I think that I've found the part no. for the wood screw, however I can't seem to find anyone that stocks it.
4204-01016-24 ws #4X1-1/2 p-rh

http://www.moll.no/pinball/parts/index.php lists that there are actually 3 of them in the machine (although, I'm not sure where that 3rd one is located)

the closest thing that I've found is that marco's has a #5 version of it
http://www.marcospecialties.com/pinball-parts/4205-01016-24

The clean freak in me is dying to clean those orange star post on that game.

Hobby Town . You can buy metal hollow rods. Than cut them to the size you need. Take the right side apart on pinball and bring the tube/sleeve with you. Ask them to cut it for you. That is what I would do if you can not find parts.

Zadom:
did you ever find the wood screws? I happened to see this today, it looks like it "might" be the correct screw:
ebay.com link: itm

edit:
I went ahead and pulled the trigger. I'll let you know if they are the correct screws (when I receive them) and will have plenty of extras for anyone with a creech that need replacements

I am resurrecting this "dead" thread. I managed to find the correct #4 screw for the top of the metal ball guides

it is part no.: 4204-01016-24 #4X1-1/2 p-rh
which is a 1-1/2" long #4 with a phillips round head wood screw

to the best of my knowledge this part is no longer being manufactured, but I managed to secure the remaining stock from a major hardware company that was closing them out about 2 years ago (I only recently re-located them).

as stated in one of my replies above, according to the pinball parts list @ moll.no, the BOM for the CftBL calls for 3 of these (I'm not sure where the 3rd one is used)

if anyone is interested, I have a small number available for sale. pricing is $4 for 3 of them, including shipping (within the u.s.)

pm me with your requests

ps
the metal tubes are magnetic, so I'm guessing steel. they have a 3/16" od and stated above have lengths of .343" and .541"

This thread is relevant to scratch building some WPC games, including WH2O. I found Home Depot (HD) carries the #4 1-1/2" p-rh, here: https://www.homedepot.com/p/Everbilt-4-x-1-1-2-in-Phillips-Round-Head-Zinc-Plated-Wood-Screw-4-Pack-808631/204587476

In WH2O, this is Part Index 1592. Part # 4204-01016-24 (1 needed)

Edit: Order from HD came in. They match up It’s refreshing to find -‘old’ parts still being manufactured.

IMG_0244 (resized).jpeg