[KLH 32 grille cloth]

This looks like the closest match from Wichelt to me: 

Item Number:

355321

Color:

Beautiful Beige

Style:

Aida

Count:

16ct

Fiber Content:

100% cotton

Width:

51"

DMC:

006/007

PrePack:

355321A

Retail Size:

1

[Need Advice Setting Up Model 20]

Looking at the manual for the Model 20 it looks like the speaker jacks on the turntable/amp are RCA phono jacks. The plugs should be available at Radio Shack or on eBay.  The manual, if you don't have one, is available here: https://www.hifiengine.com/manual_library/klh/twenty.shtml. You have to join to download but it's free and easy.