After watching a how-to video on YouTube, I took apart my eBay-purchased Gaggia MDF grinder to have a look and do a cleaning. What a mess! There was caked-on, oily, tarry coffee crud all over the inside. I had to scrape some off with a screwdriver. There were also pieces of packing peanuts from the shipment. I'll be reassembling her next and giving her a whirl.

A question: How does one tell when one's burrs need replacing?

Thank you!
Richard

From How to know grinder burrs are worn out? in the FAQ:

HB wrote:Wear indicators include coffee overheating and clumping, having to grind finer and finer, shot volume decreasing before blonding and grind time increasing.

stefano65 wrote:Easy rule of thumbs to apply to steel burrs:
run your finger against the direction of the cut ( just like you will do with a knife edge)
if you feel any resistance
still life left
if smooth and no resistance
dull

Used grinders invariably have worn-out burrs. Replacing them isn't expensive or difficult.

don't think twice - just do it.

Agree burrs undoubtedly need replacing. While I don't have direct experience with the MDF do have many years with Rocky, both 50mm flats. In my experience Rocky burrs should be replaced every 75-100lb to maintain quality grind.

RichardWalter wrote: What a mess! There was caked-on, oily, tarry coffee crud all over the inside. I had to scrape some off with a screwdriver. There were also pieces of packing peanuts from the shipment. I'll be reassembling her next and giving her a whirl.

Richard, your earlier thread about thin extractions made me think your MDF probably needed new burrs. Cleaning is fine, but it's hard to imagine such a crudded up grinder not needing burr replacement.

As so many people will be so very anxious to tell you, the MDF or the Rocky are poor investments if bought new on todays market, but your used one is quite capable of world class shots if tuned up. If your thin shots don't improve after just a cleaning, don't conclude you need a new grinder to make good espresso. Change burrs, then give it a whirl.

Thanks to all who replied!

I tried a few shots following the cleaning and they seemed better, but it may just be my expectation. I'm going to replace the burrs next. Any suggestions for a source??

Never mind! I found/bought a new set for under $50 including shipping!

Richard